Ugh, I hate them both. Crappy interface - they tried to copy mac, but in typical Windoze fashion they way over-complicated it. And it keeps asking "are you sure?" way too many times. I just bought my first mac a few months ago, and spent all of 20 minutes learning the UI. So simple and easy. My wife had Vista, now has 7, and it's just a bloated, overly-busy ripoff of Snow Leopard. I've still got XP on my office PC, and it's still working fine.
It seems Windows is sort of like 911s - every other (or close) generation is good, and the ones in between are bad