Upgrade [Gaming PC]

Hello,

I have been an avid PC gamer for a long time, I've also been building my own computers for about 10 years.

Today I am a poor uni student and I can't afford to buy as lavishly as I used to, but I still want to bring my gaming PC up to spec soon. I live in Canada, generally the website I've used to buy computer parts is www.tigerdirect.ca , but any website that ships to Canada is fine.

Here's my specs right now, if possible I want to re-use as many parts as possible. For example, my most needed upgrade right now is my processor. I know that this means I need a new motherboard, and likely new ram. I'd like to stretch my video card out for another year, for example.

AMD +3800 X2 @ 2.0GHz
Asus A8N SLI Deluxe , socket 939
2gbs ram
Nvidia 8800GTS @312mb
430W Thermaltake PSU
1680x1050 .. but since my vid card is sub-par I sometimes have to run at lower res in-game.

I know the processor/mobo need to go.. SO what's a good low-budget alternative for gaming these days? If any other info is needed, please tell!