Norton AntiVirus: 1 License for $10, or 3 for FREE

Norton AntiVirus costs $40 for the one user version at Fry's Electronics. You can then get a $30 rebate if you buy it in conjunction with some tax software product (TaxCut or TurboTax). That works out to $10 (plus tax and postage) after the rebate from Symantec. Or you can spend $45 to get a 3 license version of Norton AntiVirus (NAV). They offer a $45 rebate for the 3 license version. That makes it "free" after rebate -- strange but true. So, given these choices why would anyone buy the one license version?

I have another interesting thought. Suppose that you have three computers. You then install one copy of NAV today, another copy in a month, and the third copy in the last month. Since you have a 12-month license, is the 12-month term for each computer based on when you installed it on that particular computer? Or is it from when you installed the first copy on the first computer? Suppose that I only have two computers, and I use two licenses. If after 12 months I buy a new computer, can I still use the third license on that computer, or is it already used up?