knoppix rox for test drives. I think that Ubuntu has a live CD as well.
Ubuntu is probably the most popular consumer distribution, but Red Hat and Novell also make consumer versions that might be worth a try (fedora and open suse(?))
I gave up on Vista x64 at work and installed Centos (a Red Hat enterprise clone) - seems to work fine and I have no more trouble with it than I did with Vista. I'll eventually install a VM with XP to get the rest of the stuff that just doesn't like working through wine.
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