Is it necessary to run Antivirus software?

Is it necessary to run Antivirus software?

My pilot project is progessing well. I have a client up and streaming. When I try an image with CA Total Defense R12 antivirus loaded, the client hangs(I have waited 5 minutes) in the XP bootup process.

Is it recommended/necessary to run antivirus on the client images? If so any ideas on how to solve my problem?