I have always followed the advice to back up my registry before editing it. It is one of the few pieces of advice I have religiously followed regarding computers, probably because it is so easy to do. I don't care if I'm on my 4th beer and I've just been invited to officiate a playmate mud wrestling match next door, I always back up the registry before I make changes. Although, in that situation, I think the registry changes colud probably wait.