There is little excuse not to give Ubuntu a try. The latest release (6.0.6 LTS) comes with a Live CD distribution, which means that you don’t even have to install it and clobber your Windows PC—it runs straight out of the CD. It already contains a browser (Firefox), an email client (Evolution), an image editor (Gimp), an IM client (Gaim), a media player, and an office suite (Open Office). The OS is intuitive, the GUI is very friendly—if you are used to Windows, then the learning curve is almost non-existent.
My thoughts (and initial experience) on Ubuntu are at Technopinoy. But so far Ubuntu will make for a serious alternative for internet cafes who want to avoid spending on Windows licenses, as well as for parents who want to ensure that their children don’t waste time in games.