If you want to retain all of your playcounts, ratings, playlists etc... in iTunes, then I think the only way to do this is to use the "Backup Library" option in itunes to copy the whole lot onto DVD. These can then be imported into iTunes on the Mac. Something to do with slight differences in the config files between windows and OSX versions IIRC.
However, this stuff isn't important to some people I guess.One important note: This method successfully transfers all your song ratings and playlists, smart or otherwise. However, it does NOT transfer other metadata, like Last Played and Play Count. This, quite frankly, sucks sideways. (However, using iTunes' built-in backup and restore to 60 gazillion discs, Play Count IS transferred.)
Im fairly sure my external had drive has to be formatted for use with mac or pc. so I wont be able to use it (its a lacie rugged drive), but the firewire option sounds the best. Cheers for the replies guys.
For the mac to write to the drive yes. But my drive was formated NTFS, and I had no problems with reading from it, just plugged it in.