So I got me a 120Gb hard disk for my XBox 360 for my birthday a few days ago. Its pretty sweet and came with a transfer cable and software to migrate all my stuff from the 20Gb unit to my 120Gb unit. It feels quite a bit faster too. The demo's I have all seem to load a lot faster.
Nice. Now I can download to my hearts content and not have to continually clean up the drive.
I thoroughly recommend the unit.
I also got a new game called Overlord. Awesome fun. I get to command a horde of evil minions to do my bidding. Its a blast.