Anyone could get injured at any time, no one is immune. Priest Holmes and Fred Taylor are the only two running backs this year in which injury concerns have entered my mind while drafting.
I am more than willing to take my chances with guys like Edge, Faulk, and Portis. Fragile Fred still scare me though. It's one of those 'Fool me once, shame on you; fool me twice, shame on me' kinda things. After losing him for the year in week 2 only two years ago, I basically made a vow to never draft him again. (Remember how every year becames the year that Terrell Davis would finally be the Terrell of old, well, it didn't happen)