Sun Microsystems Inc. will complete its release of Solaris software code in the next 45 days, completing an effort the company began last year, a Sun official said Tuesday.

Sun"s release of Solaris as open-source software is an effort to expand the number of Solaris users and counter Linux and Windows growth in the data center. The first part of the code, a utility called D-Trace that was designed to improve application performance, was released earlier this year.

At its quarterly update meeting, held in the Ronald Reagan Building and International Trade Center here, Sun said Solaris 10 had received 1.3 million registered downloads.

While company officials said they have been pleased with the pace of downloads, John Loiacono, executive vice president for the software group at Sun, said in an interview that it"s difficult to know at this point precisely what users are doing with the operating system. Sun is hoping that users consider Solaris as an x86 option.

Until Sun releases its first update of Solaris 10 and then maps it back to users who previously downloaded the software, "it"s hard to tell whether someone is just kicking the tires or it"s a new installation," Loiacono said.

But Sun said vendors are responding. Hardware certifications by vendors have increased from 270 to 360 since the open-source plan was announced last year. Sun also has broad certification support for Solaris 10, and Oracle Corp. announced its certification this week. The only other large vendor Sun is waiting on is IBM, and Loiacono said the company is now working to make that happen.