You can also buy one of those over liners that everyone talks about. I finally found one at Bed Bath and Beyond for about $10. The Super Slider is about $28 or something at your local quilt store. Haven't tried it yet but I can always use it in the oven to catch spills if I don't like it on the machine.
Also someone suggested that you cut out an area for sewing and fasten the liner over the bed of the machine with some sort of tape (??) You can probably find more info on this board if you search "super slider" on here.