Ahhh – new windows. The Department of Energy says that new windows can lower your energy bill by up to 40%. That’s a pretty good incentive to replace the old, leaky ones.
Many double paned windows (single pane windows should not even be in your vocabulary) come with gas, Argon or Krypton, between the panes to help temper the heat/cool.
Both Argon and Krypton gas will improve the thermal performance of your windows. Argon is inexpensive, nontoxic, nonreactive, clear, and odorless. Krypton (insert your Superman joke here) offers a better thermal performance but is more expensive to produce.
For once however, you are probably better off to go with the less expensive Argon. Even though it is a little less efficient, it is just fine for this climate. Krypton tends to be a bit of an over-kill in our neck of the woods.
Enjoy your new windows. Make sure you get the kind that tilt in so your hubby will be able to clean them easier.