Yeah, an annual furnace cleaning and checkup is good. Some companies JUST do cleaning, so it's an idea to have a furnace company itself clean the furnace.

If the ducts have never been done, do it once. Return air registers can really get dirty. Once it's done, on with the cheesecloth or whatever.

lizbud - even in US $ that sounds like a heck of a deal. If ALL they do is cleaning though, you might want to check your yellow pages for a full-service heating company that also does cleaning...and if they are BBB members, check 'em out!