rick, I am attempting to run Mach in W7 32-bit, and have had to use DriverTest, and can confirm that it does work. I only skimmed over your thread, so forgive me if you already have it running, but if you navigate to C:\Mach 3 and then right click on DriverTest it will bring up a menu. In that menu select "Run As Administrator". This is the only way that it will work for me. Let me know how that works for you.
-Tiny