I know this is a real hot topic lately. Here's some more info from a different source (some so-called expert). Here's the article:
Q: With Julius Jones likely out for the next eight weeks, is it worth picking up ReShard Lee? How much value will Jones have once he returns from his injury?
A: Lee will likely fill Jones' role, playing a series or two a game to help keep Eddie George fresh. However, I don't think Lee has as much upside as Jones. A healthy Jones could have eventually overtaken George as the Cowboys' lead back. I see Lee stuck in a backup role unless George gets hurt. Then, there's Richie Anderson, who will be in on third-down passing situations, further complicating matters. By the time Jones returns (Week 10 or 11), it will be tough for him to make a significant impact, especially given that most fantasy leagues end by Week 16. But he could provide just the push you need to get into the postseason. If I had the choice, I'd rather use my roster spot on Jones than Lee.
Who da man? Sp_Da_Man !