While no Anti-Virus application is perfect, and Avast has its own set of flaws, AVG in my opinion is no longer a good Anti-Virus solution; it was years ago, but things have changed. I have seen so many machines as of late that have been infected even with AVG that I now rank it just a tad higher than Norton AV. The computers I have seen with the most increased malware are in order: Mcafee, Norton, AVG, and Trend Micro.
There are a few programs that are actually doing a pretty good job. In order in my opinion: Virpre (by GFI), Avast, escan Anti-Virus 11, Bit-Defender 2011, and Kaspersky Anti-Virus 2011
The rest of the applications out there either are resource hogs or do a terrible job of preventing malware or viruses.
Did you know there is actually a piece of maware out there called "AVG Antivirus 2011?" There were not shy about the name either, they named it exactly the same as the application.