I told you NAV 2003 would be unable to detect some viruses, regardless of whether or not it has definitions for them. Its scanning engine is out of date and cannot detect packed viruses. Most new ones are packed, and even old ones can be packed, thus making NAV 2003
obsolete even with new definitions.
As for Panda, I hated that one. It caused a huge performance hit on my test system. Computer Associates' EZ AntiVirus, McAfee, and Kaspersky are my recommendations. For a "home license" look into F-Prot: 30 bucks gets you antivirus for every computer in your house--without breaking the terms of your EULA. Finally a vendor that gets it!
For free antivirus, get them all.
AVG Free,
Avast and
AntiVir PE (AVPE). Of course, never run more than one real-time monitor at the same time, unless you're masochistic, that is.
Caveat:
free AVs do NOT provide the same level of protection as commercial ones. Their detection ratio, compared to commercial products, is
pathetic. Given that you seem to be a high-risk user, I would not suggest relying on free AVs. Get yourself Kaspersky and be done with it.