exhaust fan

I have a 9x5 bathroom, I have a tiled bath/shower with a full sized window in the shower, the tiles are loose and the window is crap. We are getting a 18 in high tub, and a shower surround, the surround we picked is 72 inches, I at first wanted to put a same Harvey window in, just below the ceiling, but with the tub and the surround we picked out, doesn't leave me any space for the window. I have a exhaust fan now that I got 5-7 years ago, it's rated at 70cfm, but even with the window i still get condensation on the mirror, walls and ceiling. So, I'm going to upgrade to a better exhaust fan, maybe one with a heater and higher rated cfm.
Does anybody have any suggestions on what to buy??
I'm either going to lowes or home Depot, unless someone else has a better place.
And does anybody know about the exhaust fans with the heaters?? Any chance of fires with those, since I would have insulation surrounding it in the attic???
Thanks
Barry

http://www.kair.co.uk/khrv150.htm

http://www.vent-axia.com/products/vacas/hr25.asp

Considered something like this? the only draw back is these units are 240v ac not 115 perhaps you can find and equivalent in the US.

Also you can get heated mirrors...

I am in the process of a bathroom remodel and I am looking at an attic bathroom fan. Unfortunately the smallest I have seen is 150 CFM which is twice as big as you have now. I was told by one of the contractors we had in we could put 2 bathrooms onto the fan (we have another one to remodel as well) and it would work nicely in both.

With 150 CFM you would get a lot of air through the bathroom, maybe even put 2 exhaust locations to help with air flow. This is assuming that you can get air to flow into the bathroom with the door closed. Some houses are very tightly built that it may not work. In my case I believe that even with the door closed my forced air vent would be able to supply the air needed.

Hope this helps.