gentoo is not great for beginners. dependency issues can arise -- that was my experience, at least.
redhat is a good distro. it's too bad that it's gone, but it was replaced by fedora core, which you may want to try out instead. i'm currently upgrading to that -- so far, so good.
as n0cmonkey stated, most decent hardware works. i got mine working on a tyan trinity kt-a motherboard (model 2390B) with a 3com NIC and a geforce2 mx400 video card. no problems there (see sig for more details). i don't use it heavily for anything except for ssh/web/learning about linux. regardless, it runs pretty well with what it has on it.