You'd have to find a reason for those guys to get off their arses and support Firefox to the level that IE is
As someone who is "one of those guys" I take issue with this. The reason we use IE still is due to legacy programs requiring IE6. Now I hate IE6 more than anyone else in my building. As someone who has spent years developing websites, I know the terror of IE6. But I've had it explained to me that we can support 1 browser with our resources (fortunately the webteam aren't required to follow this policy for the external websites). It can be either IE or Firefox. Due to the fact we must support IE6 only programs, we must support IE.
The vendor has finally released upgrades that don't require IE6, they don't make these upgrades available for free. And even then, companies or government agencies moving to the latest greatest program immediately is a recipe for disaster. Instead its often better to remain a version or two behind the latest developments, in order to minimise the number of bugs that will affect the system. Meanwhile other departments are asking us to invest in these other amazing systems, that have IE as a requirement. But its all good, because we already use IE. Right?
So give IT a bigger budget with more staff members and more control over what programs are purchased, and I'm sure they'd be happy to support Firefox. Most of them are probably geeks, so they probably use Firefox when at home anyway.