Norton Internet Subscription for Vista

I got a laptop and its using Norton Internet Security 2007 (kool) but the issue here is my subscription will be due in about a week from now and I don't understand the subscription stuff.

Please those who ve had similar experiences does it mean that i'll ve 2 purchase a subscription key online? because I don't understand why you'll by a laptop and still start 'buying' the softwares installed, I mean, it makes no sense

I wouldn't be posting this because I ve the installer file 4 avast antivirus but it won't run on my system because it's Windows Vista. I've searched 4 compatible antivirus software but you still have to buy them online. For those using Windows XP or previous versions I recommend avast, by the way, I still need a way to renew this subscription thing without renewing you can't update.

It talked about a product key but I don't know if it's the windows product key for my system. . . I'm confused here

Maybe if I don't find a solution, I may ve 2 uninstall the Norton and be using Windows Defender, at least it works as an antivirus, doesn't need subscription and Vista has a lot of security features

People, please advice