At my testing center the scroll wheel on the mouse DID NOT function to scroll in the MCAT browser. Also, the strike out feature on my test yesterday didn't work as well as the practice tests, especially for any diagram-like answer choice...they did not "grey out" like the practice exams. Not sure if it was a malfunction or if thats the actual function...it would put what looked like a small hyphen in front of the answer choice rather than greying it out.
Monitor was about 17" Hewlett Packard PC, pretty standard. Resolution was probably < 1024x768