I was gonna go with Apple, just because the closed nature of everything they do is bothersome to me. However, two things force me to go with MS. First, the 360 has certainly soured me on them. Releasing a product with >50% failure rate is appalling. And the whole MS points thing instead of money pisses me off, as well. The other thing is their heavy-handed approach to DRM in both the 360 and Windows. I can't play DLC on the xbox without it being connected to their server. Nor can I replace the dvd drive in it after it craps out every 6 months because of the hardware key. The anti-counterfeit measures in Windows are even worse. As much as I like their OS, I wouldn't install a legal version of it because of all the bullshit hoops they expect you to jump through. When you adopt an approach towards piracy that involves sticking it to your paying customers, I have a hard time not hating you.
I guess my problem with both Apple and Windows is their fanatical desire to maintain control of their products even after I purchase them. When I buy something, I expect it to be mine to do with as I please. Neither of these companies see things this way.