What's Open Source worth on the market?

If we want to talk about real success on the market and Linux in the same sentence, than we have to talk about the server market. However, in the past few years its expansion has stopped (which seemed to be irresistible until 2004-05, with sometimes 40-50% growth annually). It is said that the main reason for the recent bad results was that Linux's already obtained great part of the market against Unices, but nobody wants to switch from Windows Server to Linux Server. Today the estimated share of Linux is about 20% of the sales, and Windows' is about 60-70% on the server side.

On the desktop systems' market Linux is growing exponentially (see the graph below - nubers on the left are percentages of market share)...

... but it's market share is still not too significant, it's still below 1% (according to HitsLink). That's why I didn't draw Windows (about 90%) and Mac (7-8%) on this graph.

In the field of Webservers, the open source Apache is market maker (with 50%). In 2006-07, just like Linux servers, it lost big part of the market against Microsoft, but in 2008 the power relations seem to get stabilized.

On the other hand, on the browser market the different research institutions talk about very different numbers. I'm goint to use the data of HitsLink, because they're the best for trend analysis (detailed enough and available since 2004).

The growth of Firefox is slow, but unstoppable, it's going to overtake IE6, which is part of the most popular OS, Win XP.