This one tricked me for an hour or so …
In Windows Server 2008 (and Vista) there is a program called the Reliability and Performance Monitor which gives you an aggregated view of how your machine is performing.
In Windows Server 2008 you can get to it in two ways, through Server Manager or through a menu option in Administrative Tools.
In Windows Server 2008 R2 it’s not so obvious. You get to it through Server Manager, Performance and right click on Monitoring Tools.. You can also get to it through a link that says “Open Resource Monitor” on the Performance “Home Page”. There is no Administrative Tools menu option directly to the Resource Monitor, but there is a link to the Performance tool where you can again right click on Monitoring Tools.
It’s just a bit more obscure in Windows Server 2008 R2 when it was so obvious in plain Windows Server 2008.