2) What? I don't think many people will agree with you on that aspect. The fact that most Linux crashes you can just reset X and be back at the login screen, where as a Windows crash needs a full reboot means that even if Linux did crash more often - which I don't think it does - you spend less time getting screwed
3) Really? I haven't found much of a difference on my Dell laptop.
and 4) Probably true
2) My Windows XP machine hasn't crashed once since I've had it (over two years). Ubuntu 6, 7, and 8 have all consistently crashed when resuming from hibernate on my laptop (Lenovo T60, one of the most common in the world).
3) Ubuntu 8 usually runs about 45 minutes to an hour less than Windows XP on my laptop's battery.
2) There are still reliability problems. I'd include driver issues as a reliability problem.
From my experience with it, it works great if and only if you can find the right drivers. When it runs well, I like it more than Vista and most likely more than XP. But XP is certainly more supported overall, and that's another thing that's definitely worth considering.