Pillmonster: I don't think the Network-trick will work. When you ever run the updated dash -even without a network connection- and the dash detects a modchip it will set some kind of a flag, next time when you connect to xbl -modchip switched off- the flag will betray you and you can't connect to xbl.
If this is done in the EEPROM, switching to another HD also won't help. (If they start to include Modchip-detection in game xbe's which isn't really diff. to do. I know, I already mentioned this a few msg's ago)
Although, Using another HD in combination with a second EEPROM seems a very good idea.