While Firefox has some technically better features, IE is easier for me to patch using the Microsoft Baseline Security Analyser. (I have to ensure that 1250 machines are always patched up to date)

For those finding IE8 slow, re-registering one of the DLLs may solve your problem. From the command prompt do :-That re-registers the ActiveX Interface Marshaling Library and can make massive improvements to the performance.

Note that if you try this using Windows Vista, you must do this from an elevated Command Prompt window; type cmd in the Start menu Search box, right-click the Cmd.exe shortcut, and then choose Run As Administrator.