Though it might still be available at the moment, by June 30th, 2009 OneCare will no longer be sold for either servers or workstations. It is being replaced later this year by a free offering to protect only client PC systems, primarily intended for the consumer market. See the Announcement 11/18/08 thread at the top of this forum for more.
http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/ebe7e8de-c7a2-41c7-9072-24d3a2bc04ecIn your case, I'd use any remaining time from the OneCare for Server Trial to investigate other options. It's quite a bit of work to fully deploy a server based protection for multiple workstations, so any additional effort spent on an application that won't be available next year probably isn't worth the time.
There are several well established products from other vendors available and much discussion of them in the IT professional community and media.
OneCareBear
Windows OneCare Forum Moderator
