>>1
The answer depends entirely what you intend to do with it.
RHELL or CentOS if you want to install once and forget about it on purely a server; Mandrake if you want a good desktop distro out-of-box, that you have to basically reinstall from new disks twice a year to stay current; LFS, Gentoo, or Sorcerer if you want to build your own and get deep under the hood; or SuSE or anything Debian-based for a server or desktop OS that's anywhere from "not bad" to "teh win," both out-of-box (so to speak) and further down the road.
There's also Slackware, if you want to both stay current and go with the longest-lasting distro still around.
What do you want to do with your PC, not just today but three, four, even five years from now? You'll have to _luck_ into the best distro for you, if you don't answer that question.