Thanks for the Info Lyndon, it's good to know this as I was going to spend a few hundred quid on a spanky flashy network drive... so I've already saved some money!
Are you say that a standard external hard drive connected by USB to the PS3 will play direct from the drive? Only reason I ask is that I tried it before (albeit on an older PS3 firmware), and although it found the files I had to copy all the music to the PS3...... Has the latest firmware solved this?

Sorry to keep bombarding you with questions.