IMHO, the real problems on offense started when Krivsky traded away a shortstop who could provide offense (though he clearly had issues on defense) (Lopez) and a RF who could provide decent offense and good defense on an everyday basis (Kearns) and replaced them with a shortstop who could neither play offense or provide defense (McClayton) and a non-run producing RF who would be better if they played him a bit less (Freel).
I think that to solve the problems on offense, you have to start with those two positions.
In right, perhaps a platoon of Denorfia and Freel (who both seem to be guys who are best at about 110-130 games a year) would work out, although the offense lost because of Kearns is not being replaced. The Reds would be even better if they platooned in CF and Junior moved over to a corner spot.
At short, you almost have to go with a Julio Lugo to provide the pop that is necessary from that position to get things back on an even keel offensively. He is the nearest equivalent to Lopez, offensively, that is out there. That's why guys like Tejada, Jeter, Utley, (@#$%%*&) Bill Hall, Jose Reyes and A-Rod (playing SS) are so valuable; they provide offense from a traditionally defense-oriented position and greatly increase your ability to accept less offense from other positions.
Trading Dunn for pitching help would only compound the problem. If Dunn were traded, the Reds would need someone with close to equivalent production to replace him. It is not enough to replace a 40-homer, 95 RBI guy with two guys who can hit 20 homers and knock in 60 apiece, since there are only eight positions that can be filled, and if you have a zero at SS (which will be the case if they don't go for Lugo), it becomes even more important to "conserve" positions. Run producers are in short supply on the FA market this year (Soriano, Lee, Thomas, maybe Nomar if you can stand the injury risk, and that's about it). Furthermore, everyone but Lee does not fill the position Dunn would vacate, and their yearly salaries are likely north of the $10 million that is owed Dunn in 2007.
Therefore, unless Krivsky is prepared to make a huge splash and sign a Soriano-type run producer, he really should not trade Dunn unless he gets a run producer back. Now signing Soriano and putting him at second, moving BP to short (all other things remaining the same) would instantly make the Reds into serious contenders in the NL Central, but that would never happen.