Advice on automated software

Hey everyone,
I've been trying to narrow down a software package for automated trading. I'm looking for a fully automated program that can scan a large number of stocks (hundreds+) using custom criteria and then execute my strategy on any stocks that pass the scan. It would be a nice bonus if it could work with Interactive Brokers, as I've heard good things about them. Also it would be nice if the program could use level 2/time and sales info for the strategy, or at least allow me to write a plug in/app that communicates with the main program. I've looked around a bit and it seems that Tradestation might be the closest thing I'm looking for and AmiBroker seems good but I think the Interactive Brokers automated trading is in beta right now. I was considering NinjaTrader but it seems that it can't scan a bunch of stocks and then auto trade them, it can only do one symbol per strategy. Can Tradestation do what I want? Any recommendations for programs would be helpful (I've also read a little about Multicharts but I don't know how it compares to Tradestation).

Thanks,
-Scrooge