i just purchased a laptop mount and I would like to mount it directly on the floor with some self-tapping screws, just wondering if guys have done this b4 with good results (i.e. didn't cause any problems)

I would suggest getting 1-1/2 inch self tappers from Home Depot, ensure that there is nothing under where you want to mount the unit. If all is clear...go to town. You should do something to protect the screw/floor interface.