I liked WinXP -- possibly the last Windows I liked -- but if I remember correctly, the first thing power users did was de-XP-ify the GUI and switch it back to the classic, cleaner look :)
Part of it was just resources. XP ran a lot faster and better without the theming. Another part of it was due to buggy graphic drivers. But once you started getting XP on much faster computers you tend to leave it on or turn it off out of habit.
True about the resources. But back in the day we also turned it off because of the "theme park" feel it had. It felt like the classic desktop with clown makeup.
