What do I use to "fill-in" pre-drilled holes where the old cabinet hardware used to be? It looks like these cabinets have been given new hardware several times, and they just left the old holes exposed. I will be painting these laminate cabinets, any advice or suggestions would be GREATLY appreciated!

Check out wood filler and putty products at hardware and home center stores.

If you are going to paint, I recommend Durham's Water Putty. It is cheap and easy to use. Just don't mix too much at a time since it sets up fast. It can be sanded, and make sure you prime the spots before painting so the patches don't show through.