Registered: Apr 2010
Location: Continental USA
Distribution: Debian, Ubuntu, Fedora, RedHat, DSL, Puppy, CentOS, Knoppix, Mint-DE, Sparky, Vsido, tinycore, Q4OS
If you can afford it and need the licensing and support, get the current RedHat.
To add to the other suggestions above:
Generally for a desktop I would recommend either Fedora (more advanced, fast moving), or CentOS (more stable, slow progression). Fedora has more exciting 'stuff' and is updated on a very aggressive schedule: you get the latest and greatest but have to upgrade or reinstall often. CentOS is directly based upon the RHEL sources, is more solid, and its upgrade path is the same scheduled as RedHat. Both get regular security patches.
I would use CentOS as a server, whereas I would prefer Fedora over CentOS for a desktop.
UBUNTU provides a very nice desktop environment that you may also want to consider. Based (loosely) upon Debian Testing, it is slower moving and more stable than Fedora, more cutting-edge then CentOS: but with some different features than ANYTHING else. There are versions with GNOME, KDE, and XFCE based desktops that stay very current.
As with Fedora, UBUNTU has a LIVE-CD version to allow you to try it out without installing: wise if you are not sure how well supported your hardware may be!
Last edited by wpeckham; 12-12-2010 at 07:58 AM.