i had come across the soln on the net and was wondering if anyone had tried it. no one appears to have; as defender so well integrated with vista. trying it may break yr installation. best to disable it instead.
wait a sec, how do you get that msg when simply trying to disable it? is yr defender working ok otherwise ?
open msconfig > startups.disable windows defender or
open wd > tools > disable realtime protection or
open services 7 change windows defender service starup status to disabled.