I did find one possible solution that I am pursuing. They gave me an
8"x6"
auto air filter. I bought a 4" 115v fan from Radio Shack and bought wood,
flexible gutter elbow and attachments at Home Depot(~$34 in parts). I'm
going to build a fan/filter system that pumps through the filter and into
the back of the PC. Supposedly this will filter all incoming air and
create a 'positive air pressure' in the case so that all other holes in
the case push air and dust away from the computer.

Better yet... Get an external drive and put the PC into a clean environment.
Use mouse/keyboard/optical drive with long cables. Even better if you could
image the optical disks onto the hard drive.