I used Avast! -home edition... I had it in Normal protection as it is from the installation. You know what happened? I got lots of virus infections and Avast didn't tell me about them. Then I did scan the whole computer. It found Vitros, Malwares, Trojans and other Viruses about 50!
I moved them all into chess but it seemed that they just copied them again when I restarted computer. Well.. I ran Boot scan, safe mode scan and other programmes.. It removed files every time. And after every time the viruses came back.
I noted that my system files were infected so I installed repair isntall of my XP. The system started... and when I tried to scan... The viruses woke up and multiplyed themselves.. I had to format my hard drive and Install OS again to get rid of those viruses...
So YOU shouldn't do like I did! Use High settings in Avast virus protection! Or you may lose all important stuff like I lost my legal Xp and now I have cracked pirate XP:P
Btw. One of these files were "RESTORER32_a.exe" and "reader_s.exe" Avast didn't regonize them..
If you have those files on your computer you may have a very bad Virus pack like I did.. So be aware!