Got £200 to revolutionise my PC

[BahBah]

Should I get:

A dual core AMD CPU
2Gb of dual channel memory
another 7800GT gfx card for SLi ?

My existing setup:

AMD64 3500+
2x512MB Corsair XMS3200
2x36Gb SATA Raptors (I don't need more space as have servers)
Leadtek 7800GT PCIe

I am a gamer. Although when not gaming I use office stuff for making databases and websites.

Thanks

 

[BahBah]

Thanks for the input guys