Ello peeps. I'm currently building a new Gaming Computer. Only problem is that I only have $600. And I wish to venture out into new territory when it comes to parts. I'd like to keep the price as low as I can. What I'm looking for...

Games I play:
Saints Row the Third
Garrysmod
Minecraft
Source games in general (Doesn't take much for all of them)
Red Faction: Armageddon
Planetside 2
GTA IV
RTS games such as Age of Empires III, Sins of a Solar Empire: Rebellion
S.T.A.L.K.E.R. Games
Natural Selection 2
Black Mesa: Source

Other medium to high demanding games. No I don't need the Highest graphics settings, They are nice but I'm a performance and FPS man. Currently I love AMD and Nvidia, but wonder if Intel and ATI is a better choice when it comes to performance. What they hold for me, and whats the best setup, Take note that I do have extensive knowledge and background of these subjects, but when it comes to Intel and ATI, I am the stupidest person. I don't know a single thing about them. It's ok to still have AMD and Nvidia in the Build, I just would like to have some comparisons, and not just "ATI/Nvidia Sucks" or "AMD/Intel sucks".

Most recent build of 3 years ago or so.

Asus M4a79xtd Evo Motherboard
4 GB 1333 Mhz Memory
Seagate 300 GB Hard Disk
Nvidia GT 430 (This was a second hand cheap card, Didn't even perform near as good as a real GT 430)
Chiefmax 650 W Power Supply
AMD Athlon II X2 64 Dual Core 2.7 GHz CPU

Thanks