AVG's official website. And I do agree that Norton is too heavy and causes the compy to bog down.
CCleaner is awesome too.^^
This is the anti-spyware that I'm using at the moment.
As for the assurance of the trojan and malware being completely eliminated from your compy, it's no guarantee that they're completely gone especially that you installed anti-virus AFTER detecting the virus.
I know this seems too extreme but I do recommend that you reformat your compy. I do hope you have a back up of all your files and that the back up is truly virus-free/uninfected.