Well, I have a couple of books along with Vampire: Requiem ones (a game that'd be great to get running), so I have an understanding of things, but I've yet to get an actual DnD game going, so expect a couple of dumb questions. As to msn vs forum, depends on how its set up. A game like DnD would be best for msn, via forum it moves really slowly and there are people who would be impatient, along with the fact that it's not an rpg that can really be set up with as a freeform rpg, with multiple things happening. That's my 2 cents.
Edit: Is 4.0 not coming out next year?