The service pack will be part of the new version of its Windows Genuine Advantage, which will limit available features on fake copies of Vista rather than disabling programs all together.

Currently, if the WGA system finds a pirated Vista copy on a machine, which it scans for when the OS is being activated or when select Microsoft software is downloaded from its web site, the OS is essentially shut down.

However, the new version will enable users to continue to user their computers if they have a pirated copy. However, their wallpaper will turn black and a notice that the OS is a fake will appear. Every hour, a window reminding them the software is not genuine will pop up, and they will also be asked to buy a legitimate version of the OS every time they log in.

Fake Vista users will also be able to buy a genuine version of the OS at half the retail the price, which comes out at $119 for Windows Vista Home Premium for US users.

Microsoft also said it plans to close a loophole that enables people to extend the grace period from when Vista is installed and activated.