Does Windows XP Pro work for pc games???

Solution
Yes, it will play almost all games just fine. The only exception would be games that has dropped DirectX 9 support such as Just Cause 2 and the upcoming Battlefield 3. Those games can only be played on Win Vista or Win 7 since they require DX10 or DX11 to play.

Win XP only supports up to DX9 even if you install a DX11 video card.

Xp pro will work fine, however bare in mind that you will not be able to view DX10 or DX11 effects with it as XP is unsupported.
Doesn't matter either if you upgrade the Graphics card, only cure is to buy Windows Vista or Windows 7.
 
Yes, it will play almost all games just fine. The only exception would be games that has dropped DirectX 9 support such as Just Cause 2 and the upcoming Battlefield 3. Those games can only be played on Win Vista or Win 7 since they require DX10 or DX11 to play.

Win XP only supports up to DX9 even if you install a DX11 video card.

 
Solution