You could search the 80 gazillion threads that have already asked this question....
Just for entertainment puproses, alot of it depends on YOUR PC, YOUR hardware, so what "just works" for me "out of the box", may not work for you w/o ton of configuring, driver installs, etc. ATI video cards give some distros a lot of problems, others, it gives no problem at all.
I love Ubuntu 6.10, but I know there's some out there that don't like it. I hate Mandriva 07 and the newest version of PCLinuxOS, both gave me hardware problems that I couldn't get figured out. I love the older versions of Mandriva and PCLinuxOS, they both worked *almost* 100%. The only reason I switched from those two, was because I couldn't get my TV card configured, now it works perfectly under Ubuntu, with a little configuration, under every version of Ubuntu I've tried.
You're gonna get 100 different opinions(if enough people respond) in a thread like this, and you're head will be ready to explode from options. Go to
http://www.distrowatch.com and do some research and see what you think will work for you.
Here's a good Linux wiki should you decide to go Ubuntu/Kubuntu/Xubuntu.
http://ubuntuguide.org/wiki/Ubuntu:Edgy
IGF