This scenario happens from time to time. Not to worry. Here is a simple procedure to get your through. This was copied directly from http://support.microsoft.com/kb/255504. I've used this procedure several time. Also on that knowledge base article is how to transfer the roles. This should be done if you are taking one of the FSMO servers down for maintenance.
1. Log on to a Windows 2000 Server-based or Windows Server 2003-based member computer or domain controller that is located in the forest where FSMO roles are being seized. We recommend that you log on to the domain controller that you are assigning FSMO roles to. The logged-on user should be a member of the Enterprise Administrators group to transfer schema or domain naming master roles, or a member of the Domain Administrators group of the domain where the PDC emulator, RID master and the Infrastructure master roles are being transferred.
2. Click Start, click Run, type ntdsutil in the Open box, and then click OK.
3. Type roles, and then press ENTER.
4. Type connections, and then press ENTER.
5. Type connect to server servername, and then press ENTER, where servername is the name of the domain controller that you want to assign the FSMO role to.
6. At the server connections prompt, type q, and then press ENTER.
7. Type seize role, where role is the role that you want to seize. For a list of roles that you can seize, type ? at the fsmo maintenance prompt, and then press ENTER. For example, to seize the RID master role, type seize rid master. The one exception is for the PDC emulator role, whose syntax is seize pdc, not seize pdc emulator.
8. At the fsmo maintenance prompt, type q, and then press ENTER to gain access to the ntdsutil prompt. Type q, and then press ENTER to quit the Ntdsutil utility.