I want to add my GSX server 2.5 or Vmware server 3.0 to Virtual center 2.5 as a host . when i am trying for this i am getting some error related to cluster so any body can help me
You won't be able to manage GSX with VirtualCenter 2.5. See the compatability guide for what you can manage with VC 2 - http://www.vmware.com/pdf//vi3_35/esx_3/r35/vi3_35_25_compat_matrix.pdf. By VMware Server 3.0 do you mean ESX 3.0? If so what's the specific error message that you're getting?