Extend subscription for v2008

My 2008 subscription has expired.  I upgraded to 2009, then discovered that my company's VPN service did not support version 2009. I need to retain my 2008 software, but extend the subscription for virus protection.

 

I have already tried to re-install 2008, and go thru the Upgrade process, thinking this would work.  However that simply downloaded and installed version 2009 (which I have now paid for twice...).

 

How can I re-install 2008 and extend it's subscription? (and hopefully use the new subscription I have purchased)