Video Games

320GB seems a bit excessive unless you're going to be downloading a lot of films/games and storing your music collection on it. I have 160gb it's easily enough for me. I'd have a think about what you're likely to be storing on it, and see how much the extra space costs.

I'd just go for the biggest you can buy.

It wasn't long ago that desktop computer with 40GB were more than enough, till we managed to fill it up with music, and they were low quality mp3s to boot.

My 360 came with 60GB thinking it was plentiful, but I managed to fill that up within a year and decided to get a bigger hard drive simply because I brought games online every now and then, which I didn't suspected I'd do in the future.