jbrianmac,
Thank you for contacting the Live OneCare program forum. Yes, you will need to use a Windows Live ID. Or create one if you do not have one before hand.
What you can do is download the trial version onto your desktop. Then, when the program is up and running and the installation is complete, open the OneCare dashboard. Next, click Activate Now. You will be prompted to enter your product key and Windows Live ID to complete the installation.
Or... You can load your cd and use the Product Key and Windows Live ID when prompted to enter them in after the installation process.
For further assistance, please refer to the following link for how to install Live OneCare. See below:
http://help.live.com/Help.aspx?market=en-US&project=onecarev2&querytype=topic&query=OneCare_PROC_Installations.htm
Thank you for contacting the Live OneCare program forum.
Rick, MS