Hello, Bobby.
Confirm that your system meets the requirements for OneCare - http://onecare.live.com/standard/en-us/purchase/sysreq.htm?pc=CreditCard
Completely uninstall Norton. Use their cleanup utility -
ftp://ftp.symantec.com/public/english_us_canada/removal_tools/Norton_Removal_Tool.exe
Go back to the installation instructions page and review the steps to follow:
http://onecare.live.com/standard/en-us/purchase/sysreq.htm
Use the link at the bottom of that page when you're ready to proceed. You will have a 90 day trial after you install and reboot.
If you encounter any problems, there are some good Announcement posts here in the forum with troubleshooting help and also a FAQ on how to reach support.
-steve