I use both Windows XP and Mac OS X Tiger. Far and away, the Mac is my preferred platform for just about everything. I spend far more time doing maintenance such on Windows for things such as security updates, virus protection, etc. I don’t spend as much as a single second with those things on my Mac.
I work as a disaster recover specialist for a large organization with thousands of Macs and PCs. Not once have I ever seen a problem with file corruption on a Mac (except for failing disk drives), whereas I have seen those problems more times than I can count on Windows’s file systems.
Honestly, I would not trust one byte of my personal data to Windows XP. Even for those few applications where I must use Windows, I make sure to save the data files on my Mac.