Da Hamburglers Need Your Help

If anyone reads my posts regularly, you no doubt came across my posts on my fantasy team: Da Hamburglers. Our biggest area of concern is our rotation, which is currently, Francisco Liriano, Daniel Cabrera, Paul Maholm, Jarrod Washburn, and Nate Robertson. Yikes. Our bullpen is solid with Joe Nathan, Brad Lidge, Ryan Dempster, and Huston Street. I've been working on trades and I'm soliciting advice on my options. Here is what I'm working on:
Trade Joe Nathan for Barry Zito
Trade Huston Street for Noah Lowry
Trade Ryan Dempster and Dannys Baez for Kelvim Escobar/Brandon Backe and Derek Lowe
Trade Huston Street and Dannys Baez for Scott Kazmir and Derek Lowe.
I'm trying to trade 2-3 relievers for 2-3 starters. I'm pretty sure that Zito for Nathan is a done deal. I'd rather make the 2 for 2 trade then the trade for Lowry as I can live without Baez because closers are more valuable than middle/late inning relievers. So I'm likely deciding between the last 2 on the list. Breaking it down, my decision is do I want to trade Street for Kazmir, or Dempster for Escobar/Backe? If the latter, do I want Escobar or Backe? I'm leaning to keeping Street and trading for Escobar and Lowe. I appreciate anyone's input.