Supposedly the rumors say its a three-way trade.
Cubs would get Nomar Garciaparra
Red Sox would get some minor league prospects, then trade those prospects to the Arizona Diamondbacks for Randy Johnson.
The trade I guess would work, since Boston can clear some salary cap by trading off Garciaparra, which would allow them to grab Randy Johnson and pay some of his salary/resign him.
Cubs would probably only keep Garciaparra for this year only to make a run for the playoffs, and then let him free to sign with whomever team he wants to at the end of the season..
Personally I think the Cubs are covered offensively, once Ramirez gets healthy again things should get better for them. If they should trade for ANYTHING, it should be for some bullpen help. This is where they've been really struggling in this year...