I would NOT recommend running incandescent lights from a computer power supply.
As small and simple as they look, light bulbs require a LOT of power. Compare the heat generated by one of these bulbs against the chips on your motherboard/cards... Bet the lights are warmer than all chips and drives except the CPU!
Midway cocktail tables originally had two separate windings off the primary power transformer, wire runs and fuses to handle the additional wattage required by 2 lights for each player and the front coin door (6 total).
I know there have been threads here before about running second, old, AT power supplies to run the lighting, and keeping your good ATX supply for computer devices only.
Otherwise, go with LED's and limiting resistors. They barely draw any amperage.
You can also go with Cold Cathode Flourescent tubes. They pull very low power and produce a lot of light and look better than hot spot LED's, but definitely arn't as "warm" as the original bulbs. But then again they won't discolor the white panel either. You can find these really cheap online at shops catering to the automotive or computer case people who want all the flash on their possessions.