If you're ever going to take money for weddings, then you must have a vx2100 or pd170 unless you do outdoor weddings and well-lit chapels & receptions only. It really isn't right to give someone a dull, grainy wedding video just because you didn't want or couldn't afford the right camcorder. On the other hand, if you want to do other types of video work, then you're really going to want 24p capability.
But the minimum for professional wedding videography is more like:
3+ low-light camcorders (as discussed above); 3+ wireless mic systems; 3 good tripods - at least two of which must have decent true-fluid heads; 1+ 50w on-cam light; 1+ wide-angle lens; 1+ telephoto lens (rarely used, but a MUST when you need it, like some outdoor weddings on small island-like area in pond where cameras must be off-island, 50+ feet away, etc.); wedding-style animation software; a good NLE; editing computer; hand-held mic + mic stand; music loop software to fill-in those gaps; printer capable of printing on DVDs.
Oh, and TWO videographers. Husband and wife teams are best because the wife can shoot preps of bride and bridesmaids and have everyone more relaxed than if a man were there.
It's late, I'm tired, so maybe I've left something out??? Anyone else care to chip in here?