I am a firm believer in going with one of the BIG Anti-virus vendors. None are absolutely perfect but they get most of the main attacks and are reasonably easy to use for a non-technical user. My company actually resells McAfee so that is my preferred but I am have used most of the main ones with reasonable success.
If you keep them patched, most will protect you from most of the worst viruses... However, there is definitely no silver bullet.
Cheers,
Aaron
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