With the recent announcement from Microsoft of their upgrade strategy for the Windows 7 platform, it is highly unlikely that they are doing anything clandestine with regards to competitor browser vendors.
The European version of Windows 7 won't even ship with Internet Explorer.
Here are a few excerpts:
Microsoft said these upgrade options will not be available to Europeans.
"We will not be able to offer an upgrade product within Europe," said John Curran, Windows business lead at Microsoft UK, adding that only the full version of the software will be available to Europeans.
In Europe, Microsoft will send buyers of new PCs a full version of the software rather than an upgrade version. The European edition will lack Internet Explorer.
The upgrade option was not available, Microsoft said, because it was trying to comply with European competition regulations. This means that IE is not onboard Windows 7 in Europe.
This bit really makes me laugh, just like the industry experts calling for Microsoft to start distributing 3rd party product updates through the Windows/Microsoft Update interface:
A Commission spokesman dismissed Microsoft's claim that it was taking the action to comply with European laws. [snip]
The preferred remedy for Europe, he said, was to offer users a screen when they first switch on Windows 7 that gives them a choice between IE, Chrome, Firefox, Safari or Opera.