Mmmmm this was a nice weekend. I installed Gentoo Linux on my P4. Best Linux I tried on the client side. Two words: BUILD WORLD (it takes time but it is worth it). Mmmmm binaries optimized for my computer! Everything is source, so I needed to bootstrap the system. However, after building the kernel with agpgart and ATI fglrx support I had no problem building x.org and start it with full RADEON support. Mmmmm FPS!
Even if Gentoo is very good I don't see the pros of using it for my server at home. The server must be easy and fast to maintain (and does not need fancy GFX) therefore I stick to Debian there (apt-get rules!). However I think Debian is to conservative when It comes to other stuff. Try finding the fglrx driver (for my RADEON 9800 card) or x.org in their package list =).