Just in case the 64-bit editions of Windows Vista are not the thing for you, the free 120 days version of Windows XP Professional x64 is still available for download. This is nothing new, by all means. In fact the download went live all the way in 2005. These days the free trial version passed the two-year milestone since it was initially offered for download. And it's still available for download. Users have two options, either order the trial CD online or download it. Obviously, the first variant involves shipping and handling charges and only the second is actually free.

"This trial software allows you to evaluate the product for 120 days. Register to order a CD or to download the trial software. The Windows XP Professional x64 Edition trial software download is available at no charge. After you have completed the download registration process, you will receive an e-mail message with a link to the download page. The download page will include the download file and a product key for the trial software. The file will be in ISO format and must be burned to a CD or DVD before you can install the software on your computer. The download file is large-over 550 megabytes (MB)-so the download may take considerable time to complete. We recommend downloading the trial software only if you have broadband, ADSL, or other high-speed Internet connections," Microsoft revealed on the product information webpage.

Going through the registration process will immediately produce for you a trial product key for Windows XP Professional x64. The email with the download page seems to take quite some time. But since you already have a product key, I guess that a copy of XP Professional x64 could be accessed from other sources. Windows Vista comes in a range of flavors and for both 32-bit and 64-bit editions. And as far as I am concerned it is a superior choice to XP Professional x64. And via the slmgr -rearm method you can actually benefit from the same 120 days of free trial for Vista Home Basic, Home Premium, Business and Ultimate. On a side note, Microsoft announced that the 32-bit era is not over with Windows Vista. Just because Windows Server 2008 is the last server operating system to support 32-bit, does not mean that the same is valid for Vista. Windows Seven for example has been confirmed in 32-bit and 64-bit variants.