Open your /etc/fstab (you might back it up first) with your favourite editor. Add a line like
/dev/hda1 /mnt/win vfat noauto,owner,rw 0 0
You have to do this as root. Then create the mountpoint, e.g. /mnt/win
Now do a "mount /mnt/win"
Your Windoze partition should be visible and accessible now.
To have your win-partition mounted automatically, change the
....noauto..part in the fstab to ....defaults
I assume, your kernel supports the fat filesystem. The standard redhat-kernel should do it anyway.