I had some Smith Top Fuel goggles, and they fogged badly. I used some of those Scott anti-fog cloths on the inside of the lens, and that stopped the fogging problem. The only thing I didn't like was that the inside of your lens takes on this greasy/oily film. Doesn't affect vision much, but on the really hot and sweaty days, oily condensation would build up inside the lens.
This past fall I tried a pair of Pro Grip light-sensitive goggles. Temps were in the 50's to 60's, riding in a combination of fast and slow woods. Classic conditions for chronic fogging on the Smith Top Fuel and traditional goggles. The Pro Grip rep claimed zero fogging, and you know what.... he was right! I have used these on 4, 3-4 hour trail rides, and they never fogged once. Temps ranged from the low 40s through the mid-60's. We'll have to see how they do in the summer next season.
I also tried a pair of Scott Voltage Pro goggles for a day, and they were fog-free as well (same conditions).
I would invest in a good pair of anti-fog goggles, and skip the anti-fog cloth. If you can't see while riding, it really sucks, and taking your goggle off to see is a really bad idea. I know a guy that tore a cornea doing it.