Gentoo Linux is a source based distro which has excellent user forums. If you're looking for a distro to install, give it a shot. An good place to find tips and howtos the Gentoo Wiki; make sure to bookmark this site.
Here's a list of my Gentoo related blog entries:
Debian is my first choice for when I want to get a Linux system up and running fast. It's also a good choice if you want to revive an old computer. I got it working on an old PII/166 machine with 64MB of RAM. The best way to install Debian is to use the minimal install ISO which is ~180MB. The minimal install CD will get a basic system running that you can boot into. On the first boot, you'll be taken through a series of setup questions and then Debian will 'magically' install more packages by downloading them from the net. I've started using Kubuntu recently for workstations because it's well configured and works "out of the box"; I think that Kubuntu is currently the best distro for desktop use.
I've made a few deb packages for myself which you can download if you want: