The UK is in talks with Microsoft to establish a backdoor in the operating system. The government officials fear this new version of Windows could make it harder for police to read suspects' computer files.
Windows Vista is due to be rolled out later this year. Cambridge academic Ross Anderson told MPs it would mean more computer files being encrypted.
He urged the government to look at establishing "back door" ways of getting around encryptions.
The Home Office later told the BBC News website it is in talks with Microsoft.