The European Commission has praised Microsoft's initial response to its antitrust ruling against the company.
Last week, Microsoft successfully met a deadline to give details of how it would improve the way it opens up its Windows operating systems to rivals.
Microsoft had faced fines of up to $5m (£2.7m) a day if it failed to reply to Brussels by the 1 June deadline.
The European Commission will now see what Microsoft's rivals think of the plans before it makes a final decision.
In a 2004 ruling, Brussels gave Microsoft a 497m euros ($655m; £340m) fine, after finding that it had abused its monopoly position.
But more importantly, the US giant was ordered to open up its core software systems to rivals making it easier for them to build products which would work with its Windows operating system.
It also ordered Microsoft to provide a version of Windows without its own Windows Media Player, to give rival software makers a chance to compete and computer makers the option to supply PCs with the media software of their own choosing.
"I am happy that Microsoft has recognised certain principles which must underlie its implementation of the Commission's decision," said European Competition Commissioner Neelie Kroes.
The European Commission said it would now take a couple of weeks to determine whether Microsoft had met the full terms of its 2004 ruling.
"The commission is putting Microsoft's proposals to industry in order to assess them in full," it said in a statement.