I run Mandrake 9.0 on two work boxes and RH 9 on two more. Both would be good choices WHEN you're ready to dive in. As a safety measure to potential beginners disaster partitioning your hard drive, (and all of us have experienced this in some way or other..), I highly recommend looking at a cd based distro of Linux first. That way you can check out a complete Linux operating system which you boot from a cd. It is also easily downloaded and "burned" in Windows. There will be 0% danger to your hard drive.
Knoppix is the most famous of these, but I recommend Morphix-Gnome...
http://morphix.sourceforge.net/modules/news/If you like Morphix, you can then install it to HD, or decide on another distro. The Morphix installer is not easy but the advantage is Morphix is Debian based, which makes updating, deleting and installing packages via "apt-get" a snap.
Here are some others cd based distros..
http://distrowatch.com/dwres.php?resource=cd