Sony and Microsoft are both entangled in a war of fierce competition with each other over the home entertainment console market. Sony has the PlayStation 3 and Microsoft has the Xbox 360 currently circulating in the market at the moment. There is no way Microsoft will be willing to give Sony an edge in the multi-billion dollar industry by allowing Sony consoles to be able to run the Operating System while their own home console cannot.
The architecture of the Sony PlayStation 3 is not compatible with the basic requirements and specifications needed to run the Windows 7 Operating System. The PS3 only offers 512MB of RAM with the rest of the GPU dedicated for gaming and graphics.
The PlayStation 3 originally had Linux support but in an effort to cut costs and lower the price of the console it was scrapped in the newer, slimmer models of the console.