>>Any thoughts about why it would be a mistake for my next computer to be Mac?<<
Charlie Booker explained the reasons for more eloquently than I possibly could.
But Charlie's comments aside, I really don't think that it would be a mistake. PCs and Macs are equally easy to use, price points are almost identical and application availability (choice) is now a non-issue.
That said, I'm not convinced the problems your are experiencing with your Windows installation necessarily constitute a good reason to switch to a Mac. While it's often claimed that Macs are more stable than PCs, I have never seen any empirical evidence to support this. Yup, you certainly see more mention of PC problems than Mac problems, but that's inevitable as there are far more PC users than Mac users. Macs can and do crash. And so do PCs. Whether one crashes more than the other, I really don't know.
Switching to a Mac may not improve your computing experience - instead, it may simply result in your having to deal with a different, but equally frustrating, set of problems!