Makes no difference
So i've just installed my shiny new copy of Windows 7, stated it up, opened my web browser. Ah but I can't. Ooops. So how do I download and install this essential piece of software ? Given that most web browsers need to be downloaded using, wait for it, a web browser you're now stuck. However, helpful Microsoft will presumably provide an nice big 'download and install IE NOW' button on the desktop to help solve this conundrum. How many people will bother to download an alternative browser on another computer and transfer it across ? Probably not very many.
Rather than forcing MS to produce feature incomplete versions of windows, the EU commission should force MS to licence windows core technology to 3rd parties at a fair price. These 3rd parties can then create their own windows distributions with alternative software for all the main apps, different configuration and branding, (just like the linux distros do) while still being compatible with windows as a whole.