I know im a little late on this one but here goes.
If I was a Sox fan and the SOx had the opprotunity to get Lidge and Berkman for Manny I would want them to do it. While yes, Berkman did have a below-par season last year due to unjury and whatnot, over the years he has proven to be a offensive threat as well as play decent defense (not last year of coarse, but in years past he wasnt that bad, mind you, I am not looking at stats, but just from memory of watching him play and whatnot I do not think he was a bad defensive outfielder at all) and Lidge, in my opinion, is the best relief pitcher in the National League next to a healthy Eric Gagne. And not to mention that he is still pretty damn young. So regardless of the fact that Hansen, Foulke, etc.. are all capable of closing or whatever I would still have to make this trade if I was the Sox. I would also try to get a prospect or 2 in the deal as well, which shouldnt be a problem.