Good Air Compressor to clean PC's?

[Gazbirt]

I've read quiet a few threads about this, but none have answered my question. What kind of Air Compressor should I get for my store, along with Water trap and nosel. The reason I am doing this is because it will save more money than using cans of air on some of the dirtier computers that come in.

 

[Gazbirt]

Have you ever used one of the two, or know someone who has?