Although not a PC boffin, I do have over thirty years of experience, besides programming knowledge. Besides their normal source directory, its obvious that these packages create another directory for their popups and they also have other entries in the registry. Take for instance Bitdefender: (See my earlier posting here regarding crashes)
When I eventually removed it a month ago (Add remove programs) all was well and has remained so. One day while examining my system, I found a hidden subdirectory marked Bitdefender. I wiped it off.
Surprise! a week later I found another, and wiped it off as well.
It was the TUNEUP package I bought that allowed me to safely examine the registry. Although I did erase the original Bitdefender entry in
the registry, last week I used TUNEUP's 'Search' facility and checked for Bitdefender entries. I found two others in two different HKEY areas under subdirectories: Software, Microsoft, Bitdefender. These I also cleared.
Please take note. Like the wrestling shows say:
PLEASE DONT TRY THIS AT HOME.
One has to be very careful working in the registry.
I'm just trying to explain how these packages conceal their operations.
Go for the the combo AVG9 and TUNEUP 2010 They will never fail you.