Operating Systems: Microsoft Windows 2000 Professional, Microsoft Windows XP (any Edition, 32-bit or 64-bit), Microsoft Windows Vista (any Edition, 32-bit or 64-bit), Microsoft Windows 7 (any Edition, 32-bit or 64-bit) and Mac OS X 10.4 Tiger or Mac OS X 10.5 Leopard.System Requirements of Avast Pro Antivirus: Therefore additional antivirus securities are provided by different antivirus programs manufacturing companies that fight against these viruses before and after they have entered your systems. However, every bad thing makes it in a way to disrupt the good.