I used Mach2/3 on an IBM PC/XP with integrated graphics for about a year and half without major problems. I did, however, get occasional (perhaps every 10-15 hours of operation) Limit Switch stops for no apparent reason. Changing the debounce setting up to 2500 didn't seem to make any difference. I thought that this wiring related, and didn't do much about it because for the hobby stuff I do, it wasn't that much of a problem.
I came across an old Cirrus Logic video card in my pile of PC related junk, and decided to install it (XP makes it pretty easy to disable the integrated graphics and run the video off the card). I've been running this for about 4 months without any Limit Switch stops with the debounce set at 500...
I wish I could be a little more quantitative about this whole thing, but I'm thinking that the limit switch stops were caused by the well known integrated graphics problems, and disabling the integrated graphics and installing the video card solved the problem...
SF