going to get a 360, have some questions

I got A LOT of money for x-mas and now I have decided I'm going to get a 360 in a few days and I have a couple questions...

1. Is the extra 100 worth it for a xbox 360 elite, how much do you use a hardrive for, like how much memorydoes games and downloads take? 120 gb feels a bit excessive, is 20gb enough?

2. I need to know some good games that aren't like halo 3 (because thatsa no duh) that I canget for the 360.

i think the extra $100 is worth it casue the 20 gigs is used up fast. for games, go to the games sticky not sure whats its called.