Norton sucks...
I've got Symantec Corporate, which is free if you work for the DoD. Ask your computer guys if you want a copy of it.
Or get on your .mil system and get it
here.
You can also get Mcafee Enterprise.
My best bet when I'm cleaning someone's computer, is to use their updated antivirus and use at least 2 free online scans also (like Trend Micro's Housecall).
For pay antiviruses, I like Trend Micro's products.