Microsoft Corp said on Tuesday its new Windows 7 operating system will be generally available on October 22, well ahead of its original schedule and in time for the holiday shopping season.

The new operating system, which will replace the unpopular Vista, was originally planned for roll-out at the beginning of next year, but Microsoft confirmed last month that it would hit the market in time for the year's busiest shopping period.

The world's largest software company said it will send Windows 7 code to PC makers to load onto new machines -- known in the industry as 'release to manufacturing' -- around the end of July.

By October 22, people will be able to buy new computers with Windows 7 installed, or pick up the software off the shelf to install on their old computers.

Microsoft confirmed that it will run a program whereby people who buy a PC before October 22 can upgrade to Windows 7, but it not yet released details.

(Reporting by Bill Rigby, editing by Gerald E. McCormick)

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