[H] XBOX 360

[Winterlight]

I am about to order a  Xbox 360 4GB Console which I need to use as an 
Media Center extender for my SiliconDust HDHomeRun PRIME HDHR3 TV 
turner. It is the cheapest, basic XBOX 360. I assume if I do end up 
needing a hard drive I just need to plug a USB2 drive into one of the 
five ports? When you turn these on is there anything on them other 
then the OS? They don't have a DVD player so I assume all games are 
bought from XBOX Live and are downloaded...correct? Thanks