Dell McAfee Security Center

My brother bought an 8200 with the Dell McAfee Security Center.  The new computer and his old one (non-Dell) are networked.  The older computer is badly in need of virus protection update (at least, probably should be the other things too); it has VirusScan 3.x.  Ordering more from McAfee is not an issue, but I first wanted to verify whether each PC's installation of McAfee must be separately "provided for" (as it were).  If yes, then which of the various protection should be purchased to keep the older computer on a par with the protection on the new one?