Go to Start>Control Panel>add/remove programs, look for Windows Live One Care in the program list. If it is present, uninstall it. Download and run the install cleanup tool -
http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=828910&SiteID=2 Uninstall any other antivirus and antispyware software if present on your computer. Uninstall any firewall software if present ( except the Windows firewall). Go to the One Care website and download the One Care 90 day trial. If installation fails please post back the exact text of any error messages. You might also take a look at this KB article on troubleshooting installation issues -
http://support.microsoft.com/kb/910656/en-us
After One Care is installed, to activate your subscription open One Care, select "Subscribe", follow the prompts until you reach the payment page. On the payment page select "Pre-paid PIN or Token" as the payment method. Enter the 25 character product key included with your CD. Your subscription should activate.
