That is more a question for the VirusScan group than ePO, however the VirusScan Enterprise 8.8 Best Practices Guide seems to go into this with a bunch of good recommendations too.
If you don't have a copy, you can find it on the McAfee Knowledge Base (https://mysupport.mcafee.com/Eservice/Default.aspx) by searching for article:
PD22940 - VirusScan Enterprise 8.8 Best Practices Guide.
Separately, you need to know that ePO 4.5 reaches end of life Dec 31st 2013.
Now would also be a good time to plan for an upgrade to your ePO server.