w32.virut.trojan

I'm slowly resolving some severe security threats that seem to have multiple sources and behaviors.  A program known as audiodg.exe runs on my Win7 Pro 64-bit machine and I've researched it sufficiently to know that sometimes it carries the w32.virut.trojan malware.  Since no thread here seems to discuss it, I'm raising it now.  How do I know that NIS can detect this virus (trojan?)?  Searches on the Norton site end up with nothing.  

Since I know that I have had malware that NIS and NPE can't find, I need to know:  a.) if Norton knows about this threat. b.) how can I detect it and remove it? c.) Can I remove audiodg.exe, then reinstall a fresh, uncontaminated copy?