If your windows drive is on hda2 (It may be something different in your case) then you should type
mount /dev/hda2 /mnt/windows
You will have to create the /mnt/windows directory beforehand. Your USB frash drive is probably on sda, so you would do
mount /dev/sda1 /mnt/flashdrive
(once again you will have to create the mount point)
Fstab is for mounting things at boot.