Big butts
Yes.
http://www.xbox.com/en-GB/Live/Join
it really depends on what you get. If you went to target.com a 4 gb xbox is 199.99 and a 250 gb xbox is 299.99. On ebay it depends on if it is used or new.
About 300 dollars
You said it yourself: 20 Gigabytes.
The Skyplayer isnt even in the GB, its in the MB.
You download the GigaByte Module of the official website. www.terminatorsalvation.com
The main difference is that the Xbox 250 GB holds much more memory than the GB..........and the 250 GB has a glossy cover(i_e the main Xbox's body) while the GB has carbon fiber on it
if you have xbox live, u can play any multiplayer
an xbox 360 with a 60 gb hard drive costs $300 and a xbox 360 with a 120 gb hard drive costs $400
20 gb
GB means giga byte or how much memory an xbox hardrive has