Microsoft will continue to frustrate Linux users. Any fix will be temporary. It is better to look into other solutions, such as using something other than Hotmail. If enough people migrate then Microsoft will start to lose advertising revenue which is not part of their plan.
However, the determined Linux user can always beat Microsoft at its own game. It all depends on the degree to which you are willing to go. Easiest solution has been provided (using user agent). Next would be to use Wine and install IEs4linux at http://www.tatanka.com.br/ies4linux/page/Main_Page
. I hate this solution, but will post it as most people use Wine for at least something. In installing IEs4linux don't do it as root. This is a sure sign that something is wrong with the world when you start installing things not as root, but it is the only way his script works. A third solution is to try another browser in Wine such as Chromium from http://www.codeweavers.com/services/ports/chromium/
or even Safari (Windows version) installs in Wine. For the really Windows obsessed you can install Windows in a VM such as VirtualBox and everything will work because you will be in Windows (but inside a Linux host).
Best solution: don't use Hotmail and tell Microsoft to stick it for shafting its own users.