Hi Pleo,
Pete is correct - VDTM (the standard method for AV definition distribution in SAV 10) cannot function in 64-bit platforms. Those SAV 10.2 clients will need to use LiveUpdate.
Here are the official articles on the subject, with recommendations:
Supported features of Symantec AntiVirus Corporate Edition on 64-bit editions of Windows (http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2003021316524048)
Managing 64-bit clients with Symantec System Center (http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2006010609164848)
I recommend setting up a LU schedule on those two machines and ensuring there is access eithwr to the Internet LU servers or to an internal LUA 2.x or LUAU 1.x server. Please let the forum know if there's any additional advice needed!
Thanks and best regards,
Mick