The program offers information on the graphics adapter, the controllers, occupied memory, and the GPU (graphic precessing unit) temperature. In addition, it also provides general information on your system, and lets you test its efficiency.
In terms of OpenGL, GPU Caps Viewer shows your card's specs: version, texture elements, supported extensions, etc.
Lastly, it's also interesting to point out that GPU Caps Viewer includes a system that lets you collaborate (as long as you want to, of course) with graphic designers to validate your graphics card.
Windows XP and Vista (32 bits).