What's your favorite RE tool?

I'm looking for suggestions on any tools to reverse engineer programs for Windows based systems. I have the *nix and BSD bases covered; I'm just lacking a good, Windows toolkit. Particularly, tools to analyze memory, disassemble, debug, etc... I've heard positive reviews for IDA Pro, from DataRescue. Any other, [free] alternatives?

Post a comment here, I appreciate any feedback. Thanks :)

Posted by Marcin on Wednesday, April 18, 2007 in Security.