If you went and got the new 120 GB for your X-Box 360 instead of going out and buying the X-Box 360 Elite then this informaiton would be useful for you. Basically you want to transfer all the information on your 20 GB Hard Drive to the new 120 GB Hard Drive since you don’t want to lose your profile or all the game points and other information.

What you can do:

• You can stop the transfer and not lose data but you would have to start from scratch again since it doesn’t start where you left off.
• You can transfer all your game data
• You can only transfer data once, and thats it! So if your drive is fried you can’t transfer data again so do it carefully
• A CD comes with the transfer kit, following the instructions does help, and KEEP everything after your done.

What you can’t do:

• You can’t transfer movie rentals
• You can’t transfer certain Market Content, unless you get authorization online, but I’m not sure how thats supposed to work

What you do:

• Put the CD in the X-Box 360 and let the instructions come up
• Keep your 20 GB Hard Drive on your X-Box 360
• Connect the wire to the back of the X-Box 360
• Then connect the wire to the 120 GB Hard Drive
• Following the on screen instructions the transfer begins, and it tells you how long its going to take. With a full drive it could take up to an hour and a half.

Link: Engadget