Microsoft are offering a 90 day free trial of the final version of Windows 7 Enterprise Edition. Microsoft state that the free trial is for IT professionals only, however, apart from a short form to complete before downloading, they make no effort to verify this is the case.
The free download will be available until March 31st, 2010 or until a certain number of copies have been downloaded.
After the 90 day trial is complete Windows 7 will shut down the PC after an hour's operation. Users will then have to buy Windows 7 and perform a clean install - for example one that requires a reinstallation of all applications.