IMO the Halo version is just pugfugly. I mean really.. GREEN and ORANGE.
green... and orange..
...
Personally i got a used elite and skimped on the hard drive (20gig), but got a memory card to store my gamer tag (in case i want to bring my info to someone else's house)
20 gig is more than enough really, tho you really only get a usable 16gigs out of it. Can fit plenty of demos, and once ya play em why keep em. You can use a USB flash drive if you want music on there, or network it with a computer with Windows Media Center (or now if you have Vista, Windows Media Player 11.)
Luckily for me the guy who traded in the system did so with a play and charge kit
My advice:
If you don't mind spending the extra $100 go with the elite. The xbox looks FUCKING SEXY in black.
Edit:
DO pick yourself up a play and charge kit. Batteries get expensive.