iPod problem

I was lucky this year – I got an iPod for my birthday so now I can listen to audiobooks and music on the go without the hassle of running out of unique tracks after 60 minutes of CD or the joy of tapes being chewed up by old cassette playing personal stereos.
I had planned to use some of the disk space to carry documents to and from work but having used the iPod with my mac, Windows XP refuses to show it as a usable disk instead asking if I want to format it! I tried using the iPod restore software in Windows but almost broke it when it refused to give me the normal menu until I re-restored it using the restore software for the mac.
Any ideas on how to use it with both Windows and OSX would be much appreciated.