It's becoming increasingly clear that Microsoft's decision to remove Internet Explorer from Windows 7 in Europe won't end the company's antitrust problems there. In a statement released late yesterday, the European Commission explained that it believes consumers "should be offered a choice of browser, not that Windows should be supplied without a browser at all."

Now, Firefox maker Mozilla says Microsoft needs to provide more details on how IE will be made available to PC makers -- most of whom are still expected to install IE or other browsers on Windows machines bound for Europe.

"It's impossible to evaluate what this means unless and until Microsoft describes -- completely and with specificity -- all the incentives and disincentives applicable to Windows OEMs," said Mozilla CEO John Lilly in a statement. "Without this it's impossible to tell if Microsoft is giving something with one hand and taking it away with the other, and more to the point, it's impossible to tell whether this does anything more than change the technical installation process of the OEMs and make life more difficult for people upgrading to Windows 7."

Those reactions follow Opera Software's assertion that Microsoft's concession wouldn't do enough to restore competition to the market.

In its statement late yesterday, the European Commission offered a mixed reaction to Microsoft's move:

As for retail sales, which amount to less than 5% of total sales, the Commission had suggested to Microsoft that consumers be provided with a choice of web browsers. Instead Microsoft has apparently decided to supply retail consumers with a version of Windows without a web browser at all. Rather than more choice, Microsoft seems to have chosen to provide less.

As for sales to computer manufacturers, Microsoft's proposal may potentially be more positive. It is noted that computer manufacturers would appear to be able to choose to install Internet Explorer – which Microsoft will supply free of charge - another browser or multiple browsers. Were the Commission to conclude that Microsoft’s behaviour has been abusive, it would have to consider whether this proposal would in itself be sufficient to create genuine consumer choice on the web browser market.

Microsoft deputy general counsel Dave Heiner has published a lengthy blog post on the subject, outlining the company's position and offering a bit of history. He notes that "computer manufacturers and users will be free to install Internet Explorer on Windows 7, or not, as they prefer. Of course, they will also be free, as they are today, to install other Web browsers."

The company's U.S. antitrust settlement didn't ultimately prevent it from incorporating Internet Explorer into Windows, but it did put general restrictions on the behind-the-scenes deals Microsoft can make with computer makers.

Heiner acknowledges that Microsoft's separation of IE from Windows in Europe "cannot ... preclude the possibility of alternative approaches emerging through Commission processes." For insights into how Microsoft is positioning itself on the current issue in Europe, there are interesting legal and linguistic nuances in passages such as this in his post:

Since the mid-1990s governments have been focused on promoting robust competition between Windows and products that compete with features of Windows, such as Web browsers and media players. Microsoft has emphasized that consumers benefit when products such as Windows are improved over time by the addition of new features. We have also emphasized that because Windows is an open platform, including a feature in Windows does not prevent competitors from offering competing products. Others have argued that including a feature in Windows gives Microsoft too great an advantage over competing products because so many people use Windows. How these differing views are reconciled is important because consumers benefit when popular products such as Windows are continuously improved and when products such as Windows face robust competition.

We've asked Microsoft for comment on the EU and Mozilla statements, and we'll update this post depending on the response.

Post updated at 11:10 a.m. with additional details.