Elshar has given you the Windows NT 5.x answer, involving files that you don't have and that aren't used on your system. Here's the answer for the operating systems that you actually have. ☺
Your machine bootstraps into Microsoft Boot Manager, which lives on your system volume. Your Windows 7 and Windows Server 2008 volumes should only be boot volumes. You've probably got two system volumes, each combined with a boot volume. A machine needs only one system volume, and it is shared amongst all operating systems installed on the machine and separate from any boot volumes.
- Take one of your operating systems — probably Windows 7 is best since it is Windows NT 6.1 whereas Windows Server 2008 is Windows NT 6.0 — and follow Microsoft's procedure for separating out your system volume from it so that you have a separate system volume.
- Ensure that your system volume is marked as "startable"/"active" so that your firmware bootstraps it.
- Add the boot volume of your other operating system to the Microsoft Boot Manager menu on that system volume, using
- Ensure that your firmware always bootstraps from the disc that your system volume is on.
Your machine will bootstrap into Microsoft's Boot Manager, which will give you a choice between the various operating systems through its normal boot menu. You'll not need to touch your firmware settings at all in order to choose between operating systems, from then on.