At $199 when it came out, it cost about the same as the famously affordable Nintendo Wii. I can say one thing for the Xbox 360 Arcade: It is cheap. Microsoft Kinect is a motion sensor Xbox system that came out in November of 2010. This makes it quieter than the loud Elite and Arcade models.
The Elite generally has a 120 Gig while the Arcade has no hard drive.
The 360 Pro edition is split between three different hardware models. Note: Even among original Pro or Premium systems, there are divisions. However, if you're like me and can't stop buying new songs for Rock Band and hate to delete even the worst demo, you might still be filling that up as well.
These are old (read: used) Premium models that have had their innards replaced with less failure-prone hardware.
The first thing to know is what any of the 360 consoles can do, regardless of its SKU.