To each their own, but DeAngelo Williams was one of the best college running backs I have ever seen. He was all Memphis had, still performed at a high level, and took the Memphis program to levels that they rarely, if ever, see. Other than having the same last name and some shiftiness to them, I don't think that is a good comparison. I think DeAngelo is one of the top college RB's of all time. He had alot of Barry Sanders to him.
The guy I think he compares to is Joseph Addai, and that's not bad, but Addai is probably a better receiver. At best he's a Joseph Addai, at worst he's Terrence Flagler, an old Clemson RB that never made it but did finish his career with the Cards.
watch this run by DeAngelo in college. It doesn't get any better:
http://www.youtube.com/watch?v=KrkfgXNZM1M&feature=related