Adnan Tawakol :
1) i don't know
2)32 bit
3) 365 w
4)2gb (can upgrade to 4gb)
5)pentium d 945
6)hp bla bla bla but contains pci-e x16
7)100$
EVGA GTX650:
http://pcpartpicker.com/part/evga-video-card-01gp42650kr
Even with this upgrade I wouldn't try playing anything too high-end. I'd use STEAM and try a few DEMOS if possible. Your system might run the following fairly well at appropriate settings to keep high frame rate (if possible 60FPS VSYNC, or VSYNC OFF for quick games if screen tearing isn't bad). No guarantees.
- Call of Duty 2 (COD1 is 4x3 ratio)
- Call of Duty 4 Modern Warfare (on max with a GTX680/i7 I get about 180FPS average)
- Half Life 2
- Command and Conquer 3 (demo available)
- Company of Heroes
- CIV5
- Deus Ex GOTY (the first game)
- Diablo 3
- Titan Quest
- Fable The Lost Chapters
- Kingdoms of Amalur Reckoning (unsure, but there's a DEMO)
- LFD1, LFD2
- Path of Exile
- Portal 1,2
- Torchlight 1,2
Again, I'm not sure how well any of these will run so you'd want to find a DEMO if possible. Your CPU is pretty old, and the lack of System RAM may prevent some from working.