I agree with everything that Bill posted.
I just came in from using my large blast cabinet that is suppled air by a Harbor Freight 5-year old 60 gal 16 cfm 5 hp 2 stage 240v air compressor. It works fine, but it is about as small as I would suggest to use for a blast cabinet.
Check the TP Tools website for a tech tip on plumbing the air compressor for relatively dry air supply.
http://www.tptools.com/StaticText/airline-piping-diagram.pdf
