I didn't think you could just "transfer" the data from one ps3 to another (say with a usb drive), I thought that is what the copy protection on the save data is for...
I just bought a slim sometime in the past two weeks and I read where I was going to have to use the "data transfer" utility to transfer the data from my fat to my slim. Anyways, I did that, and so now I'm running my slim full time and the fat has been requisitioned to netflix duty in the bedroom.
Oh, and as far as the account activation/deactivation goes, it's Network -> Account Options.