In the past week or so I've been testing various Linux distributions to see which one fits better for my needs. For a long time I had installed (dual-boot) RedHat Linux 9.0. I have used RedHat since its earliest releases and was pleased with its stability.
However, the recent announcement by RedHat to discontinue support of its RedHad Linux products prompted me to try other distributions. I installed Mandrake 9.1 (and 9.2), Suse 8.2 (still waiting for 9.0) and obviously RedHat 9.0. Of the three, Suse (download version) appeared to be the most stable in my case, it recognized all the hardware (self build machine) with no problems, etc. While Mandrake has a lots of look and feel bells and whistles, few things didn't go well. So far in my case Suse happens to be the winner.
I also tried to install Fedora Core 1 (the 'successor'' of RedHat Linux 9.0), but couldn't get past the installation due to an error that my hard drive was full, despite the fact that Mandrake and Suse installed on the same amount of space (partition). I'll probably still check Fedora when the next release comes out.
debian and gnoppix are also good choices.