Right, first of all, get Mandrake.
www.mandrake.com
Seeing as you've already partitioned the drive it will be able to resize your NTFS partition.
SCANDISK AND DEFRAG BEFORE YOU RESIZE
just install, do an expert install and read the descriptions for the packages decide which ones you need. install the devel packages as well.
When the install is done, Mandrake will set up a boot loader for you, allowing you to choose between XP and Linux.
TBH I'd advise reformating windows if you can, just give it a 20gb partition, say, and a big FAT32 one for storage, that way you can read/write it in Linux AND XP. (Linux can't write to NTFS - well, it can, but it will corrupt your filesystem)
Mandrake has a nice installation tutorial here:
http://doc.mandrakelinux.com/Mandrak.../Starter.html/
It also covers many other aspects of using the distro.