depends on how knowledgable you are.. but check out ArchLinux.. sometimes thought of as "Gentoo without the compile times" or "Slackware with a nice package manager/updater"
It's optimized for i686 distro's so it has better performance, but won't install on an old Pentium MMX notebook I have! lol
Anyways, It's a little bit of work to get set up.. but after that.. maintaining it is easy.. Though, if you can install Gentoo.. you ca surely install Arch..