Personally, Id keep Willingham at this moment.
If we sign Carlos Pena and keep Willingham, the offense becomes a strength.
Zimmerman, Pena, Werth, and Willingham 3-6 is a very potent lineup.
I don't see us getting a standout prospect or arm for him, so moving him now doesn't really improve the ball club. His presence does.
If he has a good year, he's potentially a type B free agent. The compensation that would bring would bring in a better talent than a trade now would. Or wait to move him at the deadline when teams may be willing to overpay to land help.
Personally, I expect a bounce back year for Morgan. I know he's not a guy that's been a great player for 10 years and just had one down year, but he did hit significantly better every year in the bigs before this season.
I think a lineup of
1. Morgan
2. Desmond
3. Zimmerman
4. Pena
5. Werth
6. Willingham
7. Pudge/Ramos
8. Espinosa
Is a very good lineup. The best the Nationals have had. Thats 5 potential 20 home run guys, and 4 guys that could steal 20 bases, putting more pressure on opponents.
Sign Pena, and call it an off season in terms of the offense and major acquisitions.