Kaspersky Internet Security 2009 - 3 Users - 1 Year.
Just download newest version from Kaspersky site and use code in box to activate.
£3.33 per PC for a year cant be bad.
And yes we all know there are half decent AV's out there that can be downloaded free and that you can get this free if you bank with Barclays. I however dont bank with Barclays and like Kaspersky and the other features it offers (Parental protection and the like).
Also please note this is Kaspersky "Internet Security" not just Kaspersky "Antivirus".