Fantasy Football trade advice: Should I trade my #4 RB - D. Williams (CAR) for

TE - J. Shockey (NO)? My other TE is T. Heap, and he makes me nervous because of his injuries last year. I am pretty solid at RB, with R. Grant, W. Parker and D. McFadden. Still, Williams should have a solid year, and depth is so important. I guess what I'm asking is, is there a huge difference between Shockey and Heap this year, and is it significant enough to give up Williams?

Thanks.