This came as news to me, but it's probably old (BioShock)

[Caydr]

Last I checked - this was 8 months ago - BioShock was X360-only. Now there's a PC version on its way too, sometime this fall. Probably requires Vista though, so let's hope it doesn't suck so bad by the time BioShock comes out.

[Muzic]

According to wikipedia its Windows XP/Vista.