Havfunonline, as usual with a "wich distro" thread, I've only browsed the responses...
So, for my response, Choose a distro that grabs your interest. The biggest difference between distros that a "basic user" will notice is the package management (The tool that installs software for you). I'm sure I could make my Zenwalk installation look exactly like any other distro if I really wanted to
. Debian based distros [like Ubuntu] lean towards the programs dpkg, apt-get, and synaptic. RedHat distros [Fedora Core] can use rpm, yum, and yumex (I'm not sure what Mandriva or Suse use along with rpm). The Slackware and Slack-like [my personal favorite!] distros lean towards pkgtool and various pkgtool helpers (...probably the wrong word there...) like netpkg
Then there's Gentoo and its decendants
It's great if you want an extremely optimized system and like watching things compile. (portage and emerge are excellent tools, once you learn how to use them properly.)
Debian based distros have an advantage in that the Debian package repositories are huge
RedHat distros are great.. I don't know of any specific advantages... the Fedora Community is excellent though, as far as I recall.
Slackware (it doesn't have many 'child distros') uses a unique init system that is IMO much simpler to learn and configure, also, making your own Binary packages in Slack(and slack-based) distros is incredibly easy.
Gentoo has the advantage of automatically building from source almost every peice of software on your system. and since it installs as a very minimalistic distro (well... That may have changed in the last little while I don't know... but a stage 3 install is pretty bare-bones, let alone stage 2 or 1) only the programs and dependancies that you ask for will be installed.
(all of the above is possibly inaccurate, I'm just going by hearsay and hunch
My first Distro was Slackware, I picked it because it had a cool name.