Those fans on the side are for the A/C system, and they never come on unless your A/C is on (at least on my car). I'm honestly starting to think it's the radiator now, since the stock units are copper and are prone to clogging (had the same problem in my toyota truck). Replace it and see what happens, couldn't hurt, though it's harder to get a really hot heater in the winter with a really good radiator.
I haven't used them yet, but someone posted the link to cheap supra parts, and they have a water pump for about $70
http://www.trademotion.com/partlocator/ind...m?siteid=213747
I'm doubting it's the water pump though, as putting the thermastat in it fixed a lot of it, which means it's moving the water plenty fast, and the thermastat slowed it down so the radiator could work.