Microsoft has given its clearest indication yet that Windows 7 will be with us sooner rather than later.

The software giant has offered an approximate launch date of January 2010 for the upcoming operating system.

Microsoft vice president Bill Veghte quoted the intended launch date in a letter sent to enterprise and business customers on Tuesday.

In the letter, titled An Update on the Windows Roadmap, Veghte said: "You have told us you want a more regular, predictable Windows release schedule.

"Our plan is to deliver Windows 7 approximately three years after the January 2007 general availability launch date of Windows Vista."

Veghte assured customers that the arrival of Windows 7 would not throw up the application incompatibilities that accompanied the arrival of the much criticised Windows Vista.

"You've also let us know you don't want to face the kinds of incompatibility challenges with the next version of Windows you might have experienced early with Windows Vista," he wrote.

"Our goal is to ensure that the migration process from Windows Vista to Windows 7 is straightforward."

Long term Microsoft watchers, however, will not be holding their breath in the 18 month countdown to the arrival of Windows 7.

The company originally planned to ship consumer versions of Vista by Christmas 2006, but was forced to delay the launch by a year to prepare device drivers for the operating system.