No mater if you have a slow machine, no mater if you have a new machine. No mater what graphic card you are using, if you are a gamer or a teacher/student. Always use Debian Linux. FreeBSD is nice, but to configure the X is a pain in the ass (without being raped) literally. Gentoo is another Crap (mainly the documentation that don't show you a easy guide that work, no mater what option you chose). Ubuntu and all other Debian sisters, ask you too much memory just to start the installation, while what they give you as extra, you can have it on Debian. OpenBSD is cool if you wish to create a dedicated machine to be your firewall, but to use it as a Desktop, is another pain in the butt, because is damn slow. All other distros aren't good enough to be classified or named.