Start>Right click on My Computer>Manage. IN there you will see Drive Management. In there have your iPod hooked up. Just right click on it and change the drive letter.
And if on Vista : Control Panel --> Administrative tools --> Computer management --> Storage --> Disk management --> RIght click to the drive --> Change drive letter and paths --> Change...
And if on Vista : Control Panel --> Administrative tools --> Computer management --> Storage --> Disk management --> RIght click to the drive --> Change drive letter and paths --> Change...
Right now its "R" for my external drive. When using Windows XP my external drive was "I". I need to import my library from iTunes and the music library is on that external library. I tried changing it using the method, in which it worked, but it doesn't have an option to put it as "I".
You could just save the mp3 (or mp4) music files to your computer from your ipod, then import the files to itunes by browsing files on your HD.
This suggestion is not the best, but I am not to sure on the operations on Vista quite yet.