If you are using a Windows Vista machine to manage your Windows Server 2008 devices then you are already missing quite a few of the tool you need to do so effectively. You can get all of these tools by downloading and installing the Remote Server Administration Tools (RSAT). RSAT includes things such as Active Directory Domain Service tools, DHCP server tools, DNS server tools, and group policy management tools.
After making sure that your installation of Vista is at the Service Pack 1 level, you can download RSAT here: http://www.microsoft.com/downloads/details.aspx?FamilyId=9FF6E897-23CE-4A36-B7FC-D52065DE9960&displaylang=en&displaylang=en.
Installing this download will make sure the RSAT tools are on your system, but you must “unlock” them in order to use them. This is done by going to the system control panel, choosing Programs, and selecting Turn Windows Feature On or Off. In this dialog box, you can select the RSAT check box to make all of these tools available, or simply select certain tools individually.
Once these steps have been performed, you should have access to all of these tools under the Administrative Tools section in the control panel.