Welcome to the cafe!
I really like your team - no glaring weaknesses anywhere.
Nevin & Eaton are probably both worth picking up, but I don't know who to drop for them. Dempster is the only real candidate, and even he may have some value if he gets the closing role for the Cubs.
The only other option is to try a 2-for-1 trade to open up a roster spot. I'd look for someone who is weak at 2B, and try to trade them Iguchi & Rowand for an upgrade at OF (I don't think Rowand will do as well as last year, but he may be over-valued by some). Then you can pick up Nevin as well.