So I installed XP on this computer for the first time since I got it, about 6 months ago. None of my hardware worked. I had to boot up under Ubuntu (thank god for Gutsy's NTFS-writing ability), download the drivers and copy them over. Fortunately (unlike Linux) it was a breeze after that point. It runs really quickly surprisingly, way faster than Ubuntu, and the memory usage is much lower. It boots up a lot faster, even though that when you first see the GUI, you still have to wait for programs to load. Even with an anti-virus, it's a fair bit faster.
Yet there are some problems. Windows Live (aka MSN) won't install unless I do an update, but that's a lot of work and so I'd rather not. aMSN works fine under Windows, but it doesn't look very good (not that it does under Ubuntu, using TK and all). In fact, not much looks good. Ubuntu appears to use font anti-aliasing or something, because the fonts under XP don't look so great.
All-in-all, I am happy with having installed Ubuntu. XP may have my games work fine, but thanks to http://www.freegamage.com, I can find lots of fancy games for Ubuntu too. I'm finding both OS's offer the same features, just sometimes XP it's easier to do things (like install drivers). Although for the most part I think Gutsy is a bit of a setback, Ubuntu is well on its way to becoming the better OS.