Yeah mattK is correct. You need memory, so dont bother with the arcade at all.
The standard 360 with 60 gb hard drive is looking to cost around �160 and thats allready to go, you should have no probs getting it online.
Your elite with 120gb is looking to cost about �220-230 but it is black and you will easily be able to put 500+ music albums onto the hard drive and still have years of console/game updates/downloadable content space left. You do get a HDMI cable with the elite. This is basicly a better cable from xbox 2 Hd tv/screen and improves the quality for High definiton.
Whatever your decision its a good one. Id say the darkest games coming out for it are far cry 2. Gears of war 2. Fallout 3.