actually the "3D windows" was more than necessary move XP has GDI object limitation imposed, for example I had problem when used a theme(skin) and opened 10 apps OS would refuse to work, no new window would open nor draw, task manager would refuse to run no explorer window would open I'd be greeted by beep-error sound this was common problem and the only solution was vista's desktop composition engine (desktop window manager/DWM) with that user has no such limitation problems at all