I think the EU will sanction a proposal Microsoft made some days ago. Microsoft would provide an easy way to install the major competitors' browers. Read this statement on the Microsoft press releases page.
I can image an installed (but not fully activated) version of Internet Explorer 8 and a sort of ballot screen where you can choose your default browser. If you chose IE, then it will be activated. If you choose another browser, it will be downloaded using the IE engine and installed.
The press release contains this screenshot:
Update 2010-02-23: Microsoft has announced that Windows Update will present the choice as of March 1st, for all existing installations of XP, Vista and Windows 7. An example can be seen at www.browserchoice.eu, but the announcement shows an additional introduction to that, and explains that even existing "pinned" Internet Explorer shortcuts will be removed (which luckily implies the browser itself won't be uninstalled)...