Someone got me to try archlinux recently and I am just about to migrate my mandriva box to it. Arch linux is i686 optimized and runs extremely well on my system.
I have tried Gentoo and I do not like it when compared to Arch. Gentoo takes a lot of time (and I do mean a lot of time) to compile various applications. I can install and reinstall Arch several times in the time it takes to do a single stage 3 install of Gentoo.
Seeing that Arch is i686 optimized, all of the packages are already compiled. Arch is much like Gentoo where you have to make a lot of the config files yourself. This way you still get a really good understanding of what files do what. Arch has a great user community and they also have a wiki :
http://wiki.archlinux.org : so most of the things you need answers for are only a search away.
I would recommend Arch Linux or Ubuntu before Gentoo. Sorry, but the insanely long installation time coupled with the long compile times does not appeal to me.