Under the Server Configuration tab for my cluster, only one domain controller shows up as being used by exchange and i have 5 other domain controllers. How do I get Exchange to recognize the rest of the domain controllers?

Exchange picks domain controllers based on site membership. Additionally it can only use domain controllers that are Win2k3sp1 or later. Finally it only selects one DC as the "configuration" DC. is this the tab your looking at? If this doesn't answer your question, please give us background on your DC and Site topology.