Guys - Please help me, I have some money spend (always dangerous!)  and want to upgrade my PC for better gaming (COD4) currently the game runs OK with a few things down and AA off, I want to improve on this.
 
Current spec:
 
AMD64 x2 2ghz
4mb RAM
Point of View 8600GT
Abit Fatail1ty AN8 SLi MB
Vista32
 
Speaking with friends, they are suggesting upgrading gfx card, but I am sure that upgrading gfx might be pointless unless I now upgrade CPU and MB?
 
I would welcome your suggestions on if you think a CPU upgrade will be more beneficial over gfx card, or if getting a new gfx card will be fine.
 
Therefore, which if the aforementioned cards would you suggest?  Im reading the 8800gtx will give me more bang for my bucks at the moment.
 
Suggestions most welcome... Thanks (sorry if its 2 questions in one)
 

i don't get it, i have 8600GT and play cod4   all high 4x aa. 35-95 fps at 1024 res and 30-70 at res 1280 i don't get it how you can't play at 4x aa or are you playing at high res?

My screen is 1680 x1050, even set at lower res AA slows the game to a juddering mess. AA has to be off.
 
To be honest, my card doesnt seem to be amazing, there isnt even any power connectors on it!
 
So it still begs the question whether i need better CPU or better gfx card(?)

From my understanding, the answer is "a bit of both."
 
The 8600GT was a mediocre card; most people seem to think it was barely an improvement over the 7600GT, and worse in some areas.
 
However, I note you are proposing the 9800GX2 as a potential upgrade path.  That's a $600.00 video card, compared to $350 for the 9800GTX and less for an 8800 series.
 
How much do you really have to spend?  Because $350 bucks will get you a decent mobo and a Q6600 CPU, which is still 250 bucks less than the 9800GX2.  That's $250.00 that could still be put towards a high-end video card, solving both of your problems at once.  Get a good EVGA card then "step-up" a few months from now, or buy a second one and SLI them, when you have money again.  The disadvantage here is that the 8800s are nearing/have reached EOL so it may be hard to find one if you want to SLI them.

I don't know how AMD bound you are, but you can buy a fairly affordable mobo and CPU, and then get something like an 8800GT or 8800GTS or even a 9600GT depending on how much you're willing to spend overall.
 
If you decide to start to build a new system you'll need some new DDR2 memory.  However DDR3 has been out for a little while now so it might be worth looking at a mobo that can accept both DDR2 and DDR3 for future upgrades.  To take full advantage of more than ~3 gigs you'll need a 64-bit OS as well.
 
Something along the lines of an e8400 or AMD's nearest equivalent will be just fine for now and even for the next couple of years.  Multiple core CPU's are the way things are going so a quad might be worth it to you in the long term aspect of things.  If you decide to go that way a Q6600 or AMD equivalent is still the most bang for the buck quad.  Although Q6700's are supposed to drop pretty close to the Q6600 price tag, I don't really know if it's worth the little extra performance.
 
Don't worry about the 88** series coming to an end, they are still awesome cards and the 9 series doesn't offer much more over the 8's.  However as Jaevric said you could always upgrade no matter what with a brand like EVGA.
 
If you end up getting a high end GPU, don't forget to keep tabs on power supply needs as well.
 
It might actually make a little bit of sense to build a new system, but hold of on a new GPU till later so prices can drop a little further.  Also the 9900GTX and GX2 are supposed to come out this summer, along with a few new things from ATI as well.

You graphic card is definetly holding you back, I would suggest getting a new GPU first, and maybe a little overclocking on your X2. It will overclock mildy quite easily, an will show a good improvement with a new GPU.  
The good ol 8800GTX's are getting tough to ignore as the prices comes down. There is really nothing the 9800 series cards will do that bests them by much at all, and at ultra high res with AA turned on, the 8800GTX still is the king of the hill.
If you decide to go to a new MB and CPU, you can always carry the GPU over to a new system.

Yeah, jitpublisher is right.  If you just snagged a GPU now you could always to that other stuff later on and carry the GPU over.  The only draw back that you might have with a new GPU now is that the rest of your system might hold it back.  However you'll still see an improvement, especially with AA.

I have an x2 3800+ oc to 2.7ghz with a g92 8800 gts and I can max everything on cod4 at 1680x1050 np. J

 
Thanks - This seems the most logical step to take.
 
I dont have to buy all components at once, so will start with GPU which I can take forward onto better system(s).  I will also OC my current AMD as Im now in the mind that it has served me well and time to wring its neck a bit.
 
If the system isnt handling it too well then I can always get a new MB and CPU.
 
I would definitly go for a Quad core processor and suitable MB, any suggestions on whats best at the moment?
 
I have seen some very nicely priced BFG 786mb 8800GTX cards here in the UK, which will suit me fine for my gaming (my mate has one!)
 
I will probably look to pair up with a nice and latest CPU and MB, so any suggestions welcome........
 
Thanks again for your replies.

On the CPU & Mobo, it depends on your intentions.  Going with Intel (since that's what I just bought), the Q6600 is a very good chip and the price is about to be cut yet again, according to rumors, by another $40.00--right after I spent $199.99 on mine of course.
 
In terms of motherboards, it depends on your long-term intentions.  I bought the EVGA 780i board that can support tri-SLI because...well...because I could and because I wanted my mobo and video card from the same manufacturer.  I wanted access to SLI as well.
 
If I hadn't wanted to match my mobo & gpu manufacturers, and hadn't wanted SLI, I may well have gone with a Gigabyte Ultra-Durable/Efficient board (yay buzzwords!) and a single-card solution.
 
I would stay away from the DDR3 or "mixed" DDR2/DDR3 boards, as there's no point to going to DDR3 yet and DDR2 is cheap.

I have an 8600GT as my secondary card and it's simply not a gaming card. I use my 8800GTX for games and the difference between the two is phenomenal even with my two year old  X2 4800+.

Gaming on 16xx requires 512MB and 256-bit bus. I know bc I play TF2 on my 22" with a 8800GT. Go for the gfx upgrade!

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A better gpu upgrade for now.  
But if you plan for new mobo/cpu in near future I suggest get them now and save for gpu later because the prices of gpu's go down much faster than that of mobo/cpu.

Depends on your budget and how well you would like for COD4. Change the hardware as following:
Chagne to 8800GT / 8800GTS / 9800GTX (depends on the price difference in your country).
Check your 3DMark 06 CPU mark, if just around 1200 or lesser you may consider to change a CPU with 3DMark 06 CPU mark over 2000.