You should receive a free 6-month extension when OneCare auto-renews tomorrow. This is being offered to all current subscribers to get you over the hump to the availability of Microsoft Security Essentials, which will be the free anti-malware only product supplied in place of OneCare to work on Windows 7, Vista and XP. See the posts at the top of this forum for more.
To confirm this, you can log into your Windows Live billing account at billing.microsoft.com and click on Windows OneCare and then "renew", just don't go any further than initial renewal screen where it shows the free extension.
Rob