most popular linux distros are
Ubuntu (google Ubuntu, you'll find it),, it's kinda plug and play,, normally finds all the stuff on your pc,, fully supported by forums and community.. good choice
KUbuntu, similar to above, but with different GUI,, (used KDE instead of Gnome, KDE is typically more i candy, like windows, quite popular),, see above for the rest
both of the above come as Live CD's,, download the ISO,, burn the CD and boot your PC from the cd drive,, it'll load, and you'll see right away if there is any problems (drivers etc),,
I use Fedora Core 6 with both Gnome and KDE interfaces,, dual boot on my laptop with Windows XP..
Fedora is NOT the distro for first timers,,,