Ahh a user?
Can I ask a question. Do you keep detailed change control lists to all those things you just mentioned that the IT dept deny access to because of "paranoia"?
I thought not. So allowing you access to them so that you can call up and say xxx has happened, (without the IT bods knowing all the details) is the reason why they deny access.
I have so many users that think they know what they are doing and will deny they did anything until the cows come home. They always say I run this and that and that at home but can they tell you how it all works and why? Nope. Anyway these incidents always turn out that the user did this or that because "I've never used this thing before" or "I thought it was meant to do this" something similar.
Anyway on subject. We use IE because that is what our group heads decide. I also have Firefox deployed (yes with controls on use) because I prefer it and it is more useful for many of my users.