- Website: http://www.ollydbg.de/
- Plugins: http://www.openrce.org/downloads/browse/OllyDbg_Plugins
- Mingw Mplayer: http://www1.mplayerhq.hu/MPlayer/releases/win32/
OllyDbg is a shareware analysing debugger for Windows. Emphasis on binary code analysis makes it particularly useful in cases where source is unavailable. The debugger is really brilliant and together with some plugins OllyDbg really shines.
The main advantage with a debugger is that you can see and poke in running code. To get the target running, a mingw compiled mplayer on windows can be used. Now just use OllyDbg and its excellent breakpoint capabilities to look at the code.