Welcome to the Linux World. Here is a link: http://www.tldp.org/HOWTO/mini/Linux+WinNT-1.html
I would suggest you to do a google search and look for places such as the linux documentation project and red hat how to's. Linux is a lot different than Windows in the fact that you have to learn a lot of things by trial and error and also by doing a lot more reading and work
That's almost exactly how I have my disk partitioned, 20 for XP, 55 for data, 5 for linux (4.5 for linux / and 500 for swap).
The easiest way is to fdisk a 20 gig partition for XP, and install it. Install partition magic, set up your 55 gig partition for data, format that, and then reboot with the linux cd to let that set up the rest of your disk
Some day I'll be rich and famous for inventing a device that allows you to stab people in the face over the internet.