Distributions
Debian:
I am currently using Debian Woody with a 2.4.17 kernel from kernel.org. Alternatively Debian Potatoe 2.2.3r worked also with the unsupported X86Free 4.1potatoe port. 3.3.6 didn't work - I didn't try all that long though. I have come to the conclusion that the debian distro is in a lot of ways better than Redhat - if you spend the inital time setting it up the way you like it.
Redhat:
Redhat 7.2 works just as well. Less complicated while installing. It is the most widely distributed Linux distro available. It doesn't detect the graphics chip correctly though. So be sure to not do the X86Config while you are installing. Do it later - otherwise the install will not go through.
Mandrake:
Mandrake 8.1 is reported to have problems with the nvidia drivers. I do not know if this is really true or not - some curios things have supposedly happened. If this is really true? I don't know - but if you intend to use the nvidia drivers just go with Redhat. The two are almost clones anyway.