If you are trying linux go with Mandrake 8.1 or Suse 7.3. They both are good. In some things Mandrake is better, Suse in others.
1. Debian is a very stable distro, but it is not for you, since you aren't familiar with linux. Nice for servers though. Same thing with Slackware - not for you.
2. Redhat . Well one of the servers i have is still running Redhat 6.1 and I have no problems with it. But their 7.0 version was a disaster (to buggy). 7.1 is better (although it is VERY hard if possible to compile anything with default upatched gcc 2.96. And kernel headers aren't correct). Besides that, they Really want you to register (or you won't be able to download updates) and it is free for 1 computer only. I didn't try 7.2 and I don't want to - all they have is a name - other distros are much better.
3. Mandrake 8.1
Good:
I don't know, but i consider installation process of Mandrake 8.1 to be perfect. Easy for newbie, still gives you options if you know what you are doing. Several operating systems? No problems. Raid 5 array with NTFS partition on it? Here you go. Funky video card? I know what to do. A bunch of packages and most of them are the latest and greatest.
Bad:
Some packages might be buggy (Although there is always an update). Linuxconf and Mandrake control center are good, but not as good as yast2 in Suse. Very desktop and KDE oriented.
Summary:
It is not good for server but perfect for you to try.
Suse:
Good:
Very easy installation. Yast2 lets you do configure everything in text mode too. 2.4.10 Kernel. A lot of software and it is nicely compiled. Stable. Great documentation for a novice.
Bad:
Installation doesn't give you a lot of options - it might be very bad in some cases. It comes with sendmail and i prefer something smaller, faster and more secure.
Summary:
Good very good. But i guess they made it too easy, so it lost flexibility and fun.
Hard to say which is better - Mandrake or Suse. Try both