Woo Hoo!
I received the first full heating bill since insulating our attic to R-50. So, I ran the numbers and compared Therms of Natural Gas used per Heating Degree Day from Jan/Feb 2009 with R-50 insulation and Jan/Feb 2008 with very poor insulation. The result - 39% less Therms per Heating Degree Day used!
I also did a rough break-even calc and we should hit break-even in 5.5 years or so (depending on natural gas prices of course). Not too shabby.
More info and calculations here:
Heating Bill Before and After Attic Insulation | EcoDaddyo.com
Insulation - It's not just a good idea, it should be the law!