Sounds more like he's already got the drive working (it already has a letter right?).
To change the drive letter, go into device manager, find the right hard drive, highlight it then click on Settings. Put a checkmark under 'Removable', then change the letter to whatever you wish. After you reboot it should have your new drive letter assigned to it. Once this is done, go into my computer, right click on the drive, and then click on format, I think the default is Fat32, so you shouldn't have to worry about specifying.
And in the future if you need help, go to the forums at www.windrivers.com, from what I've seen of this place so far, noone seems to know their ass from a hole in the ground. Why the h#ll would you fdisk a drive that already is getting assigned a letter? All the guy wants to do is change the drive letter.
Anyone here ever actually seen the inside of a computer?