You must have been reading my mind regarding the counterbores, as it was very tempting just to walk over to the drill press, but sometimes I get "stubborn" and do stuff the hard way just to try the technique out...

BTW - doesn't the key for 32Bit Win7 work for 64Bit Win7 also? - its been a while since I installed 32Bit (the CNC PC is the last one in my household), but I'm sure both versions used to get shipped with one key? Mind you I don't think MACH3 runs on 64Bit iirc so if you're using the same PC for both you may not be able to go 64Bit.