I agree with Beresford, first backup the data
Many new distro support partition resize option. Since you have not specified the name of distro… I can’t comment much
But rule is same first install windows box (XP/2000/NT/2003/95/9

ha ha and next proceed to Linux installation. Most Linux distro detects the windows and creates appropriate entry using GRUB.
If you are new I recommend getting Ubuntu Linux. See old topic (information is same as XP)
http://forum.cyberciti.biz/howto-dua...-xp-vt521.html