I need help in finding legitimate information to base the layout of my testing matrix for web testing in my lab.

Ideally, we only want to keep 26 machines in our lab. I need to know where I can find what Processor, memory, and video card specs a typical user has at home and work. I need from the lowest specifications, to the highest. These need to be both PC's and Mac's. Are there any government sites that have surveys of such? We are in need of re-circulating the matrix we have now.

Thanks in advance.