Interested in extending the evaluation period for Windows Server 2008 from 60 days to 240 days? It's called a "re-arm," and Microsoft tells you how:

This article describes how to extend, or re-arm, the Windows Server 2008 evaluation period. The evaluation period is also known as the "activation grace" period. These instructions apply to any edition of Windows Server 2008. This includes evaluation copies.

Evaluating Windows Server 2008 software does not require product activation. Any edition of Windows Server 2008 may be installed without activation, and it may be evaluated for 60 days. Additionally, the 60-day evaluation period may be reset (re-armed) three times. This action extends the original 60-day evaluation period by up to 180 days for a total possible evaluation time of 240 days.

Note Although you can reset the 60-day evaluation period, you cannot extend it beyond 60 days at any time. When you reset the current 60-day evaluation period, you lose whatever time is left on the previous 60-day evaluation period. Therefore, to maximize the total evaluation time, wait until close to the end of the current 60-day evaluation period before you reset the evaluation period.