Go with the crowd. Forget frames. They are more problems than they are worth. Includes are far superior in every almost everyway.
Before you jump on the <IFRAME> band wagon siting hotmail and yahoo and all the big boys, try surfing one of those sites with a Win95 default installation. Make sure to try their European sites when you do it. If you can, use IE 3 and 4 as well. Most of the systems the big boys use have immense back ends that can deliver HTML 3.2 because they actually care about people who don't upgrade their computers or browsers. Unlike most of us. I'll spare you the blurb on demographics and consumer spending...
Cheers