You'll need to add a line to your /etc/fstab file. For this I'm going to assume that your windows partition is the first partition on the first drive. If not, you'll have to change some numbers:
First type this into a console:
Makes a directory on which to attach the windows drive (because linux uses one big tree for all filesystem)
Then add this line to the bottom of your /etc/fstab file:
/dev/hda1 /mnt/win_c vfat users,user,auto 0 0
Both these bits will need to be done as root. I'm also assuming that your windows drive is fat32.