McAfee AntiVirus Plus 2011, UPG. Software type: Upgrade, License quantity: 3 user(s). Minimum hard disk space: 200 MB, Minimum RAM: 256 MB, Minimum processor: 1.00 GHz. Compatible operating systems: Windows XP SP3 (32-bit) Windows Vista SP1 (32 / 64-bit) Windows 7 (32 /64-bit)