ECU upgrades are only as good as the mods you have installed. They are usually programmed accordingly, and most often the "last piece of the puzzle." From the mods listed in your sig, I wouldnt recommend dropping the $350 on one, I doubt you would even notice a difference. (It may crispen up the throttle response a bit).

JET is one well known ECU re-programmer http://www.jetchip.com/, and here is an article with good results from them:
http://www.fourwheeler.com/projectbuild/129_0303_xt/

Upgrades to a vehicles ECU are usually needed and highly beneficial when tuning a forced induction application and increasing the boost from stock.

What else do you have done to warrant an ECU upgrade?

You may search around locally, in hopes of finding a shop that can install a piggyback "engine management system" and tune it on a dyno. That method is more worth the money than blowing it on some generic chip, and most of these systems are re-programmable with a laptop, in the event you want to change or tweak something.

Have a look at these links for more information:

http://www.haltech.com
http://www.aempower.com/product_ems.asp
http://www.motec.com/products/ecu/control.htm

There are more out there, but those are the ones I know of off hand.