Sun is not any more generous than any other IT vendor, but is instead giving away Solaris 10 as a way of blunting the perceived freeness of Linux and in the hopes of getting its vast installed base of Solaris customers excited about upgrading the Solaris on their existing Sparc box or moving to a new or old X86 box to run the operating system.

Having seeded a very large installed base of potential Solaris 10 users–not every download ends up being a used piece of software, obviously–Sun is banking on the fact that many of those downloads will end up in production environments where customers insist on buying Sun support for the operating system.

So far, Sun’s top brass will not say what their conversion rate is on turning those free downloads into money. Both Scott McNealy, Sun’s CEO and chairman, and Jonathan Schwartz, who is risking his professional neck as president and chief operating officer on Sun’s new pricing strategies, say they expected that turning installed base market share into money would take time.

Nonetheless, Sun will probably see some action on this front late this year and early next, since customers really only got their hands on the Solaris 10 code in February and need 6 to 9 months to test the software before they will move into production for projects. And, given the fact that the Solaris 10 for X86/X64 servers is still being built out, this may take a little longer for the two-thirds of customers who have opted for the X86/X64 version of Solaris 10 as part of those downloads.

Sun is tracking closer to my initial optimistic estimates from March, when I built a model for Solaris 10 shipments. It is hard to say where this curve will go, but almost certainly it will take a bend downward at some point. It is hard to imagine 9 million cumulative Solaris 10 downloads by December 2006, which is the optimistic estimate I made back in March.

But I think that the pessimistic estimate of 3 million downloads by December 2006 is turning out to be too cynical. As I said back in March, I think it likely that actual downloads will shoot the gap between these two estimates, with probably 5 million to 6 million cumulative Solaris 10 downloads by the end of 2006.