I am starting to learn reverse engineering and wanted to know what tools people are using and what the pros and cons are to each. I have been using .Net Reflector to reverse engineer .Net apps but I also have to work with old COM dlls and it would be great to figure out what they are doing. Many of the developers who wrote them didn't check the code into source control and the binaries are out on the production servers. Any help would be appreciated.
Ollydbg is a great free tool for analyzing and debugging native apps and DLLs. Also the various tools from HeavenTools are really useful. Native code is not quite as easy as reversing .NET, you'll generally need a solid foundation in x86 assembly language to get very far.