Best thing i've found to keep my dash clean is an impregnated cloth designed for lifting toner spillage. Mesh cloth with a slight rubber texture. Works a treat, leaves no dust behind and doesn't leave any of the cloth behind either.

Working in I.T. does have at least one benefit then.... i get a nice factory fresh dashboard.

The way I clean it is to use an ordinary sponge, warm water and car shampoo (Halfrauds Catatonic Advanced is good as it has no wax). Lightly wash it, then use a fine paintbrush to brush up all the dust whilst hovering a vacuum cleaner hose end - works a treat!

I use a chamois leather and that seems to do the trick. I also have a 1 inch paint brush in the car. I use this to dust the awkward air vents and hard to reach corners whilst I am stuck in traffic, at the lights etc.

To do the windows I use a household window cleaner and an old newspaper. Learnt this at work on the trucks, it really does the business and is free!