If you are going to use just one hard drive I think Mandrake is the way to go. I use Red Hat. But I always suggest using a separate hard drive if possible.

Windows / Linux dual boot with two drives ( I know, I'm shameless )

With two hard drives, it does not matter what version, just what boot loader is used.

All have their strong points, Red Hat and Mandrake are easier ( IMHO ) to maintain ( they use RPMs )