I've been a board lurker on here for quite a while, but I figured I'd chip in with this bit.
I really appreciate the time and effort you took to get the ball rolling on this roster, so I decided to lend a helping hand. I'm a big Cowboys fan so I went through their roster and made the necessary tweaks pre-Free Agency. First, I've added all of the Cowboys current rookies you didn't get to yet (DeMarco Murray RB, David Arkin OG, Dawyne Harris WR, Josh Thomas CB, Shaun Chapas FB & Bill Nagy C). I also converted Bruce Carter to an ILB, which is what he will probably play in our 3-4. Second, I went through the entire Cowboys roster and tweaked their ratings to reflect their play from last year (such as dropping Marc Colombo down to a 76, Doug Free up to an 86, Alan Ball down to a 73, etc). Overall I ended up lowering more players than raising them. However, the team still has relatively high Offensive and Defensive Ratings, which is probably due to highly-rated players at key spots (such as Romo at 87 and Ware at 94). Don't know how to fix that myself.
To make way for the rookies, I cut a few players from the team - mostly depth players who may not be in Dallas next year. The biggest names I cut were Marion Barber and Marcus Spears, both of whom are heavily rumored to be on their way out of Dallas.
So until Free Agency madness lands, I'd say this Cowboys roster is very accurate. I tried to be as impartial as possible when tweaking the ratings. If you believe there should be any changes, go right ahead and do them, you're the roster maker!
Also, I dropped one of the Charger's safeties and added Bob Sanders to the team, just because it was bugging me that he wasn't there. <_<
Since this is my first actual post, I'll be PM'ing you the updated file. Hope it helps!