Unfortunately there is no other option. You use the software you're given, and that's it.

If you're browsing random sites that could well be infected, even if you weren't using IE7 the fact that you're on a "secure military network" doesn't stop you from being just as vulnerable as anyone else browsing random sites. Sounds to be like the security of your network has at least one hole in it.

You can't even use an upgraded version of the browser? IE7 kinda defeats the point of a "secured" network.