As long as you don't mind editing the registry it's pretty easy
Run Regedit
In the registry you go to the key:
HKEY_CURRENT_USER/SOFTWARE/MICROSOFT/INTERNET EXPLORER/MAIN
And then look for the entry marked "Window Title", double click on it and enter the new text you want it to display. If the key isn't there then create a new string variable with the name "Window Title", double click the entry and change it to whatever you want.
Then exit regedit.
Close all internet explorer windows and the next time you open IE you'll have the new text displayed.
Oh and