How to extend the Windows Server 2008 evaluation period
You probably already know that you do not need to activate Windows Server 2008 for 60-days evaluation period. In most cases 60-days default evaluation period will be just fine. It is possible to reset 60-day evaluation period up to three times for total evaluation period by up to 240 days. Cool right? ;-)
Article ID: 948472 How to extend the Windows Server 2008 evaluation period