to do this you need to edit your /etc/fstab (as root) to include the line:
/dev/hda1 /mnt/windows vfat rw,user,umask=000 0 0
of course this assumes that the windows drive is at /dev/hda1 and that you want to mount it to /mnt/windows. (You also have to issue a "mkdir /mnt/windows" as root too if that directory does not already exist)
Hope I helped - Good luck!