Avast seems to be good ! it run on
In my opinion no matter how huge is the database for the antivirus software, by deleting the virus from any computer it will delete some registry keys with it ... the computer will keeps acting wired even after cleaning.
until now there Antivirus softwares will not restore registry values when it will be changed due do infections.
conclusion, we need a powerful firewall ! + Antivirus like AVAST !