Pre-release versions of Windows Vista expire May 31st. If you are running a pre-release version of Vista (Beta 2, RC1 or RC2), you'll begin to see notifications of the upcoming expiration around May 18th, according to Microsoft.

Microsoft does suggest migrating to the final version of Vista before the May 31st expiration to avoid any disruption in service. Those who participated in Microsoft's Customer Preview Program had a pre-release version of Vista Ultimate installed. To install the final version of Windows Vista, you can purchase the desired Windows Vista Upgrade.

In all but one instance, you will need to do a clean install of Windows, so back up any data you need. If you have Windows Vista RC1 installed on your computer and you buy the Windows Vista Ultimate Upgrade version, you can do an "in-place" upgrade, which does not wipe all of your programs. It is still recommended that you back up your data before upgrading either way.

After May 31st, people who continue to use the pre-release versions of Vista will be limited to 2-hour sessions. After two hours, the PC will reboot without warning, giving you no opportunity to save your data. Microsoft says the opportunity to log in for these 2-hour sessions will be for a limited time, but gives no specific time frame for the cut-off.

Windows Vista Home Basic, Home Premium, Business and Ultimate, full and upgrade versions, are available from Doty Computers.