for example, for my own disk:
/dev/hda will represent the whole disk, i.e. with my 5 different partitions.
/dev/hda1 will represent my windows (vfat) partition, /dev/hda5 my LFS root (ext3) partition, /dev/hda7 my /home part etc...
To find which file (with Linux, everything is file) represents your windows partition, you have to know how your hard disk is partitionned (for example windows first or windows beetween / and /home)... this will give you an idea of the unknown
number...
If windows partition is first, you will have to type:
mount -t vfat /dev/hda1 /mnt/windows
if that's not the case, have a look at /etc/mtab or /etc/fstab, to have an idea of its range. This files will show you a match between /dev and partitions...
If you have nothing understood... send the contents of /etc/fstab