I am looking to buy a portable air compressor, what sort of output do I need to power a impact wrench/drill etc?.

[Edited on 10/4/10 by LBMEFM]

Impact wrenches will work of smaller CFM ratings, but air tools like drills/sanders need alot.

14/15CFM (not free air rating) work of 13Amp sockets.

I have had an cast iron 15CFM compressor fo 20 years plus and has done alot of work.
cost about £400/£500.
I bought 2 Direct drive cheapies and both went wrong withing 6months.

The other option is petrol/diesel. not had any experience of these.