I would recommend Ubuntu 9.04 to start with. It's what most of us here locally are using. Ubuntu is a variatnt of Debian which is the basis for a couple of other 'flavors' of Linux.
Ubuntu and Debian come with WSJT, fldigi, and gMSFK as supported software installs. You'll also have other Amatuer radio related software to pick and choose from in the Synaptic package manager ranging from Sat tracking to NEC antenna modeling software. All open source software...:) You will even be able to upload to the ARRL Logbook Of The World even. Another benefit is that if you want to run PSKmail, you will be able to. I have set it up, but not done much with it other than to know that it works. I would recommend that you find a local Linux Users Group (LUG) in your area to attend as that usually is the BEST source of information on any problems that you may encounter. Here's a link to a few in that might be close to you for help: http://www.linux.org/groups/usa/westvirginia.html Just do a search for Linux User Groups in your favorite search engine to find others. Hope this helps some. James W8ISS