We are getting ready to paint the outside of our house and I wanted to know if there is a big difference between those expensive brand name paints or getting something cheaper. What exactly is the big difference between these two types. I do agree with the general "you get what you pay for" but there seems to be a range of options so I want to understand the difference. Thanks for your advice.

It is not so much the paint as it is the prep work before the paint. Make sure it is an exterior paint.
Painting with a roller and brush will last longer than a paint job that is sprayed on also.
http://www.youtube.com/watch?v=1EBp7UoPQsE

Exterior latex is fine for painting a house.

Duron, Behr, Valspar, Dutch Boy are all good. Don't get cheap paint. It won't cover well, washes out and will cost you money in the long run. C******** G******* has rated Behr #1 for a couple of years.