Window frame choice will depend somewhat on the style of your home. Frank Lloyd Wright's Prairie School style of architecture can stand the inclusion of metal frame windows because of the contemporary look. But, a Queen Ann style home built during the turn of the last century might lose flair (and some value) if existing wood windows aren't replaced with wood.

Although vinyl frames insulate slightly better than wood frames, the difference is negligible. Depending upon what kind of glass is used in the window, a wood-frame window can end up being a better insulator. Both wood-and vinyl-frame windows insulate better than metal frames.

The smart way to shop for windows is to compare U-values. Every window sold has a U-value rating. The lower the U-value the more insulative value the window has. U-4.5 is a relatively low rating. U-6 wouldn't be as good, but U-4.1 is better.

We like vinyl-frame windows and we like vinyl- and aluminum-clad wood-frame windows, too. We don't want to sound like politicians, but we like metal-frame windows as well. However, our guess is that as time goes on we will begin to see more wood- and vinyl-frame windows and fewer metal-framed ones. In some homes, so much condensation occurs at metal frames that the adjacent area mildews, and in some instances wood rot also develops.

By the way, modern wood- or vinyl-frame windows are far superior to the wood-frame windows of yesteryear.