This is NOT true with AVG with most e-mail clients. The user must scan manually on most clients. However, Microsoft Outlook and Microsoft Outlook Express are far more at risk from viruses in attachments than other e-mail clients. For example, I use Opera browser and its e-mail client, and I "get sent" many viruses not picked up by AVG in real time, and I save them to my desktop and then scan them by right-clicking...and sure enough they are viruses, but could never execute because Opera's e-mail client is not at risk of executing attachments just by viewing the message.
If you use a version of Outlook, AVG will assist you in real time, and if you use another client then your risk from Viruses is far less and you can scan manually with AVG. Either way, AVG is a great anti-virus that is WAY less invasive to your system than the "big two" and is free! I have used many virus scanners and I have found that if AVG is kept up to date, that it detects everything the big boys detect, and is a lot faster in manual scans.
As to AVG's "repair capabilities:" by being reasonably careful, despite a network of 6 computers at home (wife, 4 kids, and me) plus controlling a desktop and two laptops at work on a major network (using Norton Corporate there--not my choice), plus college kids bringing in computers and hooking them up here, and running servers on both home and work computers, I have never in my 35 years of computing (started 1969) been infected by even one virus. However, using AVG (and its supplemental programs they have on their web site) I have disinfected many viruses from the computers of family and friends, and it always worked great.
Nothing is perfect, but I think that users should feel nicely protected using the Freeware version of AVG and should not worry that they should buy one of the "big boys."