Upgrade or buy new?

If you can get the parts alot cheaper on Ebay go for it but unless you can get both for under $160ish then I would not bother

Also, is the 9850 gtx as far as I can go for a gpu? Any other more recent gpu that would work and offer an improvement? I thinking no since they are all PCI express 2.0 from what I've come across thus far, but figured I'd ask anyways.

You can use PCIE 2.0 card in the PCIE 1 slot it just has half the bandwidth which makes little difference unless you are running seriously high end cards and even then not that much. So basically you can run any card.

Well that's good news..been out of the build scene for a number of years..thanks Simon that gives me more options at least..if the price is right

If you upgrade your existing rig, it'll probably cost you less than getting a new system. But, you'll eventually get a new system anyway (I presume), and probably not too far in the future as your current rig is dated by today's standards. So you'll end up spending more in the slightly longer run if you upgrade your existing system now and then get a new build several months down the line, as opposed to getting a new system now.

Yes I have been weighing the pros and cons and unless I can get an exceptional deal for both a cpu and a gpu..I will most likely hold off for an i5 complete overhaul.

Since it took you quite a while to want an upgrade from an Athon X2 4200+, your processing needs must not be very much therefore, upgrading to a Phenom II X4 945 will be a big jump.

You did not specify what is the main use of you PC. If gaming, then a CPU upgrade makes more sense. You can then use the savings from a new mobo & CPU & DDR3RAM to buy a newer nVidia card (depending on your budget & need based on your monitor resolution) and use your 9850GTX as a physx card. It will extend the life of your PC for a few more years while improving your gaming experience CPU & GPU wise.

The graphics cards are both transferable to any new build so you don't have to worry that these investment will go to waste.

Did you read the product specs for that mobo? It looks like the Phenom II X4 945 is the fastest it will support with the latest BETA BIOS.

currently you have a 1.0a or 1.1 pci-e you can run a pci-e 2.0 card in it without any drop in performance other than the bottleneck of your cpu which will criple any card over a 96gt. it doesnt halve bandwidth or have any other issues other than bios compatibility. if your motherboard has a via chipset or sis chupset then you many not be alble to run 2.0 but if its n-force 550 or greater then you should have no issues.
problem is if your gonna play games you need something with a little more grunt than an athlon dual and its likley as you have an m2n sli you biggest cpu choice will be limited to the 6400x2 although putting in a p2 quad sounds apealing with a beta bios your never gonna see the true potential of the cpu because it can never stretch out as the HT bandwidth is a quater of what it should be for that cpu. so again the idea is nice but the money you spend to the performance you would gain , aint worth it.,

the 9850gtx isnt worth the price to performance not when you consider the low end pci-e 2.0 cards smash it to pieces for less than 100 bux.

so what your looking at to play the latest games is a full new build in reality...

you have a case a psu and the other bits and bobs so all your looking at is the cost of a motherboard/ram/cpu and gfx. 700bux will get you a midrange gaming monster
500 will get you a powerhouse media center

Not knowing the main purpouse you use your pc for, my suggestion would be:

upgrade to an I5 2500k system. It has great overclocking potential and is very fast for any purpouse. If your graphics solution i'sn't causing you problems at the moment you can also choose to upgrade it at a later time. The suggestion to keep it as a physx card is a nice one btw. The money you initialy save this way could be used for another great general purpouse speed upgrade: a SSD

Your board supports the Athlon II x 3 445 & x 4 640 & the Phenom x 4 820 & 945 any of these would be good upgrades. As for the GPU a Radeon 5770/6770 would be good matched with these CPUs, maybe even up to a 6850 or Nvidia 460 above these a more up to date CPU & motherboard would be needed to get the best from it. If it was my machine I would get the cheapest of the of the CPUs I listed and a Radeon 5770/6770.

Thanks everyone for the response. Prior to our two children, it was a gaming rig that I built with the intention of upgrading to a Phenom when time and budget allowed for it. Well, with the two kids, priority and time for gaming has been near null until just recently I have had more free time to indulge.

But given the number of years, I am well past the point where I planned on upgrading and I have been heavily weighing on a complete mobo, ram, cpu, gpu overhaul. But with the holidays etc, any i5 build will have to wait until the reprecusions to the wallet from the holidays has been dealt with but a chip upgrade and a newer card that I could implement in a few months in a new i5 build in crossfire is something I been thinking of. I guess my real question would be with a newer card (I was thinking a 6850 giving how well this card scales in crossfire or less likely a 5770 since you can get one for less then a 100.00 right now) and the Phenom II X4 9.., will the upgrade be servicable enough for playing any of the newer games more specifically Star Wars, BF3, Skyrim?

Then come the i5 upgrade time I would drop the 9800gtx back into it the old system with the phenom cpu and allow the mrs to use the system as is and get a second 6850 for an i5-2500k crossfire build in the coming months.

To answer HEXit, it is a nForce 590 Rev. A2.

Edit: Just did a quick shopbot to get an idea on pricing for a cpu and the cheapest thus far without getting into ebay yet is $92.00 for an Phenom II x4 925. Looking at the Phenom II x2's still looking over 100.00 through online suppliers. Checked out ebay and from what I seen thus far, the 92.00 isn't a bad deal.

Check out this link (comparing the AMD Athlon X2 4600+ to the AMD Phenom II X4 940). It would be a 2-3X boost in CPU power. In my no where near humble enough opinion, it would be worth $120 or so to try a CPU upgrade.

I think the 9850GTX was very powerful in 2007, and may be good enough for many games up to 1680 x 1050.

However, if you decide to upgrade the GPU, you should get the best modern one you can afford. That way you, if you find the CPU upgrade isn't enough and want to jump to an I5 system, you don't need to buy another GPU.

If you want to make the jump to an I5 system now, you can reuse your case, power supply, hard drive, and CD/DVD drive. You need a CPU, motherboard, RAM, and GPU. As you can see, to go to I5 you only need two more components than trying to upgrade the old machine (Mobo and RAM). So, it would cost about $175 more to go to I5.

If you do the CPU upgrade and then decide to go to an I5, you are out the $100 for the CPU upgrade (unless you have a way to resell it).

Chew on that info!      

Thanks Rick, awesome link! That is excellent hard fact comparison. Especially when you compare the two you have listed and then again the 940 to the i5 2500k.

As to the gpu set on a 6950 now..not to mention the HAF 912 case when I jump to the i5. I'm going to do both now. A Phenom 920 upgrade given the difference in the benchmark is next to nill to the 940 so the family will have a system and they can keep their paws off of mine! I have two bronze modular cpus a 620 and a 550 so I'll save on that portion though might just get a 700W+ with the 6950  

edit: on a side note in regards to devoting the 9800gtx+ to phys. I come across negative results from a few different sites when using higher end cards with it. The higher end card is slowed down as it waits for the older card. Not sure if this is the case for every combination, just repeating what I've read elsewhere.

I though you mentioned you have a 650 Antec in your first post.

But if the 620 PSU you are referring to just now is the Corsair HX620, you do not need to upgrade at all if you only have 1x6950. I myself power 2x6950, AMD PII X3 unlocked, 4xWD500GB Black & no problem with the Corsair HX620. But if yours is not the Corsair HX620, then perhaps you need to upgrade.

Id just upgrade it.

That motherboard you bought "m2n-e sli" was a blessing. It has a bios update out to support phenom ii x4's.
Not very often, will that happen.
Check ASUS official cpu support list. It has grown heavily with a bios update.

Of course somebody probably already said, what i just said. I didnt bother reading the posts, cept for the OP's.