QUOTE(hardcandy @ Apr 15 2008, 05:18 PM)
First, do not delete anything until the serial number is transferred. You may delete some info needed to ID the xbox in transferring the serial number.
If the previous owner had a Live account or registered the Xbox360, they may have to transfer ownership to you. May need to call Microsoft Xbox support to find out how to transfer the serial number to your Live account.
If you have a live account already set up,Live Migration
I would guess go to the System blade, go to Memory, then delete any videos,demos,music,etc you do not want. Go to Network, see if their is an option to reset to factory defaults. Then reset Video and Audio to factory default (if there is an option).
I don't understand what you mean by transferring the serial number. Isn't the SN on the back of the Xbox 360? Also, Can you only have one Xbox Live account per Xbox 360? I know the person who sold it to me, so I can get them to help me. Can I just call MS, have them transfer the ownership and warranty info to me, and make my own Xbox Live account?
Keep in mind when replying that I know very little about Xbox 360 or Live. I have an old Xbox that I use for XBMC, but that's about it.