You need to install EPO on a server. On each client you install a agent which then communicates with the server. You can control policies, pattern/program updates, where clients get their updates from etc etc.
If you have a large number of virusscan machines you should definitely be running EPO. Without it you will be running around like a headless chicken. EPO is the best thing since sliced bread! 🙂
I don't think they do a trial version though, but check out the docs here:
EPo is only free if you have purchased licences for a relevant product suite eg Total Virus Defence ( VSE/groupshield/epo/siteadvisor ent), it is possible to have VSE 8.5 and not have a licence to run EPO. Although I can't find the links now there were trial versions available not too long ago (I think they were 60 or 90 day)
As soon as I posted, I wondered if I might be wrong! I should have researched it further. 😮 Since I've been involved with McAfee, I've always had one of the suites (AVD, then upgraded to TPE-A), so it's always been free to me.