Here's a more comprehensive guide which also includes instructions on how to transfer your existing data onto the newer larger hard drive:
http://forums.xbox-scene.com/index.p...ic=660096&st=0
I ordered a 120GB western digital scorpio bevs hdd from ebuyer yesterday & will be aiming to do this upgrade on friday. The £ saving isn't as huge as it could have been but the drive is £39 and I already have a sata interface so I'm ready to go. I anyone's interested how I get on I will update here after it's fitted.