Detours is really cool. Last I checked (last year?) it was free for 32-bit code, but you had to pay for or license the 64-bit version. There's an open-source (b

Detours is really cool. Last I checked (last year?) it was free for 32-bit code, but you had to pay for or license the 64-bit version. There's an open-source (but not 100% functionally-equivalent) alternative called EasyHook: http://easyhook.codeplex.com/ http://easyhook.codeplex.com/ An anecdote: I've got a Sony VAIO Z series laptop, one of the 2010 models with "Switchable Hybrid" graphics -- that is, there's a switch marked "Auto"/"Speed"/"Stamina" which you can use to switch between the embedded Intel GPU and the discrete nVidia GPU. The laptop itself is great -- probably the best developer's laptop I've ever seen/used -- but drivers have always been a real pain. Anyway, as it turns out, I was updating the drivers last week and just happened to notice the Detours DLL within the driver installer files; so it seems that the graphics driver actually just checks the position of the switch and uses Detours to direct any calls to the "real" driver for whatever hardware is selected.