I think the CFM rating for most PC fans is somewhere between 50-80.

PC fans run on 12V DC, with a mA rating (milliamps) that varies from model to model.

Radio Shack sells variable adapters that can provide a variety of different voltages, from 6V DC up to 12V DC. They're used to replace lost adaptor plugs for radios, scanners, any kind of appliance that runs on batteries but can be plugged into a wall outlet as well. They cost about 20 bucks or so.... I buy them and cut off the end, then wire them up to the PC fan... Slide the switch over to 12V, plug 'er in, and voila. PC fan starts spinnin'.