In reply to jasonC abroad:
I had a Henry in the UK and it was fine, but it's not easily available in Norway, so I have a Karcher WD 4 Premium, and it's fantastic. I'm renovating (read, rebuilding) a 200yo wooden house, and it extracts dust and dirt quickly from pretty much anywhere. I used it to suck up a large amount of plaster chunks too, no problem.
The bags aren't advertised as re-usable, but they definitely are, it's just a bit of a faff emptying them.
Karcher is the default brand for cleaning machines here in Norway.