Rambler,
Repairing "dual pane" windows is for the most part, better left for the professional. Now, don't get me wrong, I'm all for fixing things myself and, saving a buck here and there. But, when those windows are built/manufactured, it's done in what's called a "clean room". The glass is seriously cleaned and sanitized. Then, it's placed in an assembly that involves a sealant of Butyl, and it's done in a vacuum. The vacuum is what keeps the interior clear and without moisture which, if it infiltrates, will show up as fogging. Once it's in there, it's almost impossible for a layman to do a home repair on his own.
The reason is, it's almost impossible to duplicate the assembly conditions that would repel the moisture and keep the vacuum in place.
There's been one or two on here that have had some success with messing with their own windows but, it is not the norm. There are a couple of companies that specialize in the repair of those dual pane windows and, from what I've read here, they're very reasonable and fast in service.
Scott