No, Just Cause 2 will not run under Windows XP. JC2 only has a DirectX 10 codepath for rendering, there is no DirectX 9 support. DirectX 10 is not compatible with Windows XP. There have been attempts to hack DX10 support into XP but none were successful. If you want to play JC2 on PC you'll have to upgrade to Windows 7. (or Vista, but why would you want to do that)