To dual boot linux and windows:

Install windows first. If you install it second, it will overwrite the MBR and access to anything else will be lost.

In the linux installation process, make sure it's pointed at the right partition then let it format that partition for you.

Best not to select the reiser format, it's no longer being actively developed. Choose ext3. Herr Reiser has more pressing concerns these days.

Expect a certain amount of hassle in opening windows files. MS deliberately causes problems. Power Point is the one I have the most trouble with.

Ask for help when (not if) you need it.

Download and try some live cd's first to help you choose the flavour that suits you best.

Ubuntu and Fedora have the largest and most active user bases. Check out the forums. I like SuSE despite that.