3 year old home built system needing some help

There isn't a big increase in performance in just replacing the MB and MEM. Going with a newer MB would open up future upgrades, but IMHO save your money and do a new build down the road.

What you can do now is overclock the Phenom. Pick up a Hyper 212 EVO CPU cooler and you can get to a stable overclock of around 3.4 - 3.5GHz. That CPU cooler will also carry forward and can be used in a future system as well... A video card upgrade can also carry forward to a new system and can benefit you now. The 550w PSU can handle quite a bit. Maybe an HD 6870 for around $150 after rebate...

Id personally say grab yourself a new graphics card now (your 550w PSU should be fine for anything up to GTX 560Ti or 6950). This will certainly increase performance over your 8800GTS.

You can then transfer this card over to a new build when you feel you have the money to do so. Z68 motherboard and i3-2100 might be a nice upgrade path for you without costing the earth   or even the i5-2500k if your pockets go a bit deeper  

Presumably, this is a gaming pc, and you want to improve it.

Do you have a budget?

In general, a graphics card upgrade will improve your gaming the most, or at least let you improve the eye candy.

To help clarify your options, run these two tests:

a) Run your games, but lower your resolution and eye candy.
If your FPS increases, it indicates that your cpu is strong enough to drive a better graphics configuration.

b) Limit your cpu, either by reducing the OC, or, in windows power management, limit the maximum cpu% to something like 70%.
If your FPS drops significantly, it is an indicator that your cpu is the limiting factor, and a cpu upgrade is in order.

It is possible that both tests are positive, indicating that you have a well balanced system, and both cpu and gpu need to be upgraded to get better gaming FPS.

If you think you need more graphics power, then your psu should be able to power the following cards:

GTX550ti needs 400w with 24a on the 12v rails plus one 6-pin PCI-E power lead.

GTX560 needs 450w with 24a on the 12v rails plus two 6-pin PCI-E power leads.

GTX560Ti needs 500w with 30a on the 12v rails plus two 6-pin PCI-E power leads.

GTX570 needs 550w with 38a on the 12v rails plus two 6-pin PCI-E power leads.

If you think you need more cpu power, you could try to overclock your current cpu, but I would not expect too much there.

If you will change the motherboard, you might as well consider a change to a sandy bridge cpu. They are stronger than AMD on a clock for clock basis.
ivy bridge is due out in a few months, offering even 15% more. Faster DDR3 ram is not a good reason to change out a motherboard; it makes only a minor difference.

If your budget does not permit a full rebuild, I would get the graphics upgrade first, since it should make the most difference, and it can carry forward to a new build.

What about an SSD? It might not help gaming all that much but it will make everything else on the computer seem much faster.

So I went for the big increase for now and picked up an EVGA GTX 560 Ti. I tested it with Skyrim, and auto detect went from low settings to Ultra. As for frame rates and what not, I doubt I'm getting the best I can on Ultra settings, but it seems smooth for as little as I have played it so far.

Onto my processor, is anyone familiar with the phenom II 940 black edition? I've bumped it up to 3.3 from 3.0 just using auto overclock in my bios. What can I expect out of it if I take it any further with stock cooling?

Thank you all very much for your replies, they are very much appreciated!

You can expect a max OC somewhere around 3.5GHz on that revision of CPU (C2). On stock cooling you are might already be pushing it a bit... Check your temps.

I haven't seen my main CPU temp go over 58c under full load, is this too hot?

Under full load for how long? It is best to download / run Prime95 and let it run for a while while monitoring temps. Under 60, after the CPU (all cores) has been running at 100% for an extended time, is good.

It was probably a couple hours on prime 95. I'll set it up to run awhile longer today and keep checking it.

After I get the CPU stable, there's not much left I can do with this system I'm assuming? I'm just trying to get as much out of it before a rebuild this coming year.

Is upping my ram from 4GB to 6-8GB going to make any difference in general gaming?

No game will use more than 2 or 3gb by itself.

If you are multitasking, more ram can help.

Here are some of the types of help you can get from 8gb:
http://blog.corsair.com/?p=65

You guys are great.. Thank you so much for all of your help! I really appreciate it!