Here is my plan: At the end of the week I am deleting any friends that haven't gone online with Xbox Live since a few weeks ago. Xbox Live on 360 tells you the last time each of your friends were on, so if you don't go online in the next few weeks, you are out of the will.
Anybody else "starting fresh" with the new system?
PS: If you want to be friends again (as this is nothing personal), just send a friend invite with text or voice saying who you are.
