I support windows on a daily basis. I find that it is named aptly as it is easy to break just like a window. Too many moving parts and the clowns at my office rush to deploy things they do not understand and it of course has ramifications that are long reaching and take a very long time to fix. This coupled with the fact that they deploy in mass and do not even verify it went without any problems only intensifies the affects.
So with that many moving parts and the fact that it has issues, that MS screws with everything with each new release including the CLI, has seriously screwed with perms everywhere and finally the new feature where it send info on how you are using the software and a multitude of other data that I cannot locate specifically YET. For these reasons and having to learn everything all over again moves me to learning something else. Linux is something that I am moving toward. Yeah sure there is this standards thing between versions, but for the most part the CLI isn't all that different and I can count on it.
So back to IE, firstly never tie your browser and your OS that's asking for trouble in my opinion. Browser flaw leads to OS flaw and vice versa. Why would you set such a thing up. Your browser is a public facing application, your OS should be a private facing matter.
MS has made the OS more secure? Hmm, well the browser still functions as it did and it's so secure now it takes a multitude of tweaking to access COM+ items just to fix them. If you are going to make that kind of move ensure that your COM+ items don't need fixing.
If I were the UK I'd be looking for another OS. I myself am moving to Linux on all the home machines. Sure I'll have to learn something new, but I am being forced to do that every few years anyway on a much grander scale, so I might as well move to something that I can bank on it's foundation not changing so much.