Do the sneak perks Muffled Movement and Silence make your character completely silent or should I start murdering poor Adrianne and reloading to try and get a generic set of Muffle boots?

Muffle movement reduces the noise from your armor by 50% when sneaking. Silence I think add another 50% to Muffle which allows you to move quicker in sneak mode with making a noise. You could just use the Illusion spell Muffle as well. In fact if you playing a sneaky assassin I highly recommend going into Illusion. It make that type of a character a lot of fun imo.

Yeah, I'm working Illusion now actually, at least until I can get Quiet Casting. Can't beat Fus Roh Dahing enemies without them knowing where I am. Repeatedly casting Muffle is a bit of a pain though so I guess I'll start beating up Adrainne and reloading. Thanks!

Muffle isn't the same as sneak as they'll still hear if they can't see you, Forsworn especially seem to have the hearing of a cat.

I saw a vid somewhere demonstrating this but I can't find the link.

They went on to show how light armour is much better than heavy for going un-noticed. You could conduct an experiment, especially if you can get to apocrypha and cash in your perks, or use the console to remove a few and add them in again. Just pick a city guard and see how close you can get to them before the eye icon begins to open. The results would be interesting.

I'm thinking of doing an experiment to find out just what level of enchantments are worth having on armour at the moment.

Muffle puts the character in a Cone of Silence so he can't be heard. Sneak, otoh, relies a lot on Hide In Shadows. Silence without adequately hiding will get you spotted. Likewise, hiding but making a lot of racket will also get you spotted. Combining the two ... "What was that? I must be hearing things again."