The other thing not mentioned is that most modern cars automatically turn on the A/C when the defroster is switched on engaging the "dehumidifier" canister and reducing inside fog much faster.
You may just need to clean all the contacts on your fan, etc. and ensure your old swede is putting out as much heat as possible to help dry up the inside.
Checking your floor mats for water saturation as previously suggested will also make a huge difference, You want it as dry as possible.
That defog stuff from rainx makes the moisture bead up and drop off the window so you can see out. Great for vision, but then you have drips everywhere around the car, tried it once in the wagon, good idea turned into a big mess. :).
-Erik