Make a pre-filter cyclone for it to catch the bulk of the dust - that way
the bags last ages just mopping up the very fine stuff.

http://codesmiths.com/shed/workshop/...ques/cyclones/
http://www.internode.co.uk/cyclone/

--
Cheers,

John.


Great links. I've occasionally thought about trying that myself. (I'm better
at thinking than doing).