CNET posted a story that Newegg has Symantec Norton AntiVirus 2013 for 3 PCs for free
Get Norton AntiVirus 2013 (3 PCs) free after rebate
That's after paying $45 and redeeming a $45 mail-in rebate (PDF), which comes in the form of a prepaid debit card. (And, please, don't tell me it's "not really free." That's Symantec semantics, people.)
The software is designed to remove and prevent viruses and spyware, and according to most leading tech outlets, it's a champ at both. CNET rated it five stars, calling it "a highly recommended paid security option for Windows computers." And PC Magazine awarded it an Editors' Choice, noting that it "beat all other current products in [our] malware removal test and rated high with the independent labs as well."
Get Norton AntiVirus 2013 (3 PCs) free after rebate