If this anti-spyware software is being released as part of the windows "package" then all updates, upgrades, hotfixes, etc are on the windows update site. Anytime one updates windows it checks to see that the windows installation is legitimate.
I pretty certain that people with a downloaded version of Windows have no trouble updating and nor does the update check your OS. At least that's what I've heard . . . .
Since I have Windows 98SE and the ani-spyware only works with Windows 2000 and above I'll just stick with Adaware which works great. Never had a thing on my computer. . .