Computer after virus

Hello,
I had a virus and I removed it with 3 tools:Avast!, MBAM, aswMBR.
After the initial removal of the virus, I performed another full scan at each tool separately, just to be sure there are no more viruses left, and really, no infected files were found.
So, my question is, if the anti virus/anti malware program says that there are no viruses/worms, can I be sure of that? or the viruses/worms are still left hidden on the pc and damaging my pc / stealing my passwords ?
Thanks every 1 who is answering , I just really want to know if it is safe to use the pc that was infected and now is said to be clean by the anti virus/malware.

What would help is some more information, file name, location and malware name from the avast detections and attach the MBAM and aswMBR logs.

EDIT: Having just seen your other topic (http://forum.avast.com/index.php?topic=95772.0), this question could best have been asked there where the information is and a qualified malware removal specialist is present.