Mandrake is a good choice.. the latest official release is 10.0 which is very stable and easy to use. As far as a how-to I suggest just jumping in, the installation process is very good at setting up your machine correctly. Once you're up and running, you'll find that it's not too difficult to use coming over from Windows. I like using KDE desktop manager myself, although Gnome is another option. Choose the one you feel most comfortable with. You can also get a few doc files from mandrake that will show pretty much how to do everything you need to know from using all the included apps to running command line:
Unfortunately, the latest docs are from MDK 9.2, but not much has changed to 10.0 and it'll help you get a little familiar with the install process and such..