Here's a way around the conundrum, but it may be too involved for your bro.
- get an iPod and connect it to your Mac in disk mode.
- copy the mp3 files onto it in the Finder.
- send iPod to brother.
- tell brother to plug in iPod before installing software (so it will automatically use disk mode on his Dell -- hopefully it's running WinXP)
- copy music from iPod to hard disk, then delete it from the iPod
- disconnect iPod
- install iPod software and iTunes and reboot
- plug in iPod -- it will launch iTunes then ask to be associated with his computer
- add the music to the library
- sync the iPod
This is the easiest way I know to get the music onto his computer and still allow him to modify the contents of the iPod from his PC.