Ubuntu is like OSX, it restricts access to a lot of stuff that shouldn't be restricted. Scientific Linux is a clone of RHEL and is more enterprise-oriented, so you won't get all the bling (by default), but you will get easy access to whatever you want, you get stability and support for about 10 years IIRC.

Gotta go now though, I'll be back later tonight or tomorrow to give a proper answer, but now: If Anything Happens To The Cat!