Window and sill replacement

[mkeogh]

All,
Since my wife and I moved into our house 3+ years ago we have haed the windows. As far as we can tell they are pretty low grade, wood windows and are extremely drafty during the winter, and every summer we end up fending off the hordes of wasps and other asorted insects that get past them.
We have finally decided it is time to replace them all and we are meeting with a contractor in the next few days to discuss our alternatives.
He is currently proposing replacing each of the windows with American Weather seal replacement windows. These are 2 pane, argon-filled vynl winidows where both panes fold inward for eay cleaning. He will be stopping by with additional literature next week. Does anyone have any comments on this window brand?
While replacing the windows are are also planning to replace the sills since several are rotted. Is there a composit sill material alternative to wood? Or is wood or wrapped wood our only alternative?

Thanks,
M

[grumpydasmurf]

I've never heard of this brand. You want to know if the windows have an AAMA rating, silver is good and gold is better. Some windows have none. Also check to see if these windows have a NFRC approval.

You want to know the R value and U factor as well.

Fusion welded or mechanically fastened frame? What type of balance system?