Re: Windows vs Linux, a few observations
Heat and battery life:
It's very simple, really. As programs and operating systems get more development done on them, they grow in size. When they grow in size, they use more memory and more processing power. (also referred to, unflatteringly, as "bloat")
Windows XP Professional was first released in 2001. Service Pack 2 was released in 2004, without much of an addition to the original codebase. The latest Xubuntu was released in 2007. So really, Xubuntu uses 6 years more memory and CPU power than Windows XP. If you decided to run Windows Vista instead, you would find that the bloat would be much worse than Windows XP, and most likely worse than Xubuntu.
I hope my advice helps. Please let me know whether it did!