I chose Marshall Faulk. The guy has had back-to-back MVP-caliber years, and I doubt next year's going to be any different, especially if the Rams add Johnnie Morton. I would have voted for James this time last year, but The Edge is coming off of a serious injury, and as such, he's a big question mark for this upcoming year.
I hope Ricky Williams is the best RB next year, but I doubt he will have as many total-yards as Marshall Faulk next year unless Faulk gets the injury-bug.
Although Willams is my favorite back, and has been since he was drafted, I think Edge has, thus far, been the best pure back in the league. I agree with 054 that Marshall is great, but he is an all around back and I voted on pure RB ability so I give a slight edge to the Edge (not U2's.)
Ronnie, I can think of one missing RB and have one question. First, Anthony "A-Train" Thomas should definitely be up there as one of the top backs. I also question putting Dunn up there at all. He's a good third down back at best but not an every down back and certainly not one of the better backs in the league. Good poll anyway though.