Doors and Windows - Improving seal of exisiting windows??

Hi........I have a 20 year old colonial in New England built with builders quality "Bilt Best" thermopane windows. I have noticed some air leakage and the weatherstripping looks dried out. Is it worth researching and replacing weather stripping or actually is there something better to do to seal the windows? Otherswise windows are solid and in good shape. OR are the new energy efficient windows really the way to go but at a BIG expense? With oil costs ahead..........ayayayayaeee!!!

My guess would be that they are two pane glass, nothing more, no argon, no lo-E coating, no nothing. With energy costs soaring, new or replacement windows would be your best bet. But there are often local glass/storm door dealers that may have the weatherstrip material that will help some of the draft problems.