I have installed a 500 watt power supply, cut two 3" holes in the case, and installed identical fans in those locations. One in the top (drawing air out) and one in the bottom, (drawing air in) The bottom one is centered approximately midway between the outside edges of the motherboard.
To accommodate the fan that draws air in from the bottom. I installed four casters in place of the plastic feet, which has lifted the bottom of the computer 2" above the surface it sits on.
While this has not dropped the case temperature, any lower than what it was with the high performance fan, that I had installed in the old power supply. It has improved the stability of the computer.
Although I have yet to put it to test under a heavy load, the temperature does not rise as high as it did before, when opening the resource heavy programs.
I used a variable speed hand held drill with a metal hole cutter. Not an easy task even for those with extensive power tool experience. I am pleased with the finished product, however it would have been a complete disaster with out the information in the link that was provide by Doby.
Thank you all.