I have not had an anti-virus program installed on my computers for years. Since running so many OS's, that don't suffer from the virus plagues as do the Microsoft products, but I do use the DOS versions of both, BitDefender & F-Prot, on a bootable CD-ROM for scanning user systems. They can also be used on a bootable floppy if needed.
The larger AVP just seem be suites these days, and are not really necessary. When you see the size of Nortons - 25meg programs or more, for scanning virii. When F-Prot is less the 2.5megs, and does the same thing.