This Norton Anti-Virus software, licenced for three PCs, loaded easily and activated with the supplied code - once you have an account created the next two PCs activate just by logging into your Norton account. All three licences count down 365 days from the first PCs activation date. So far, 50 days in, Norton AntiVirus has run perfectly on our 32-bit XP and 64-bit Windows 7 PCs. The Norton interface looks very pretty and seems fairly easy to navigate, and it runs with few, if any, pop-up warnings to deal with [great for gamers]. Plus there's no noticeable hit on our PC speeds. For more details and PC system requirements check on-line at Symantec. When you leave the PC alone idling, Norton Anti-Virus rummages about checking for malware.
We also have the far more expensive Norton 360 v5.0 on other PCs that goes beyond this standard cheaper Norton Anti-Virus 2012 and adds in a `smart' firewall, on-line identity protection, social networking & parental controls, PC Tuneup and backup with 2Gb available on-line. In practice we don't really use the extra applications in Norton 360 as I have the key ones in stand-alone packages [Registry Mechanic and Norton Ghost], so in future I'll probably stick to this far cheaper Norton Anti-virus and the standard Windows firewall.
Norton Anti-virus 2012 now has PC Tools Spyware Doctor incorporated which goes far further than the likes of Bullguard and FSecure in detecting and removing nasty malware like `XP Anti-Virus' persistent pop-ups.
So a decent, quiet and relatively cheap anti-virus program. Also check out PC Pro's A-listed Trend Micro Titanium Internet Security 2011 and freebie AVG Anti-Virus Free Edition. Generally it's always cheaper to buy a boxed edition from Amazon than via download, so make sure you order well in advance of your licence expiring, as these days anti-virus software drops dead the second the years up.