I am not tech support, just a regular user, but I have using OneCare since its early beta stages in 2005. First is your XP laptop running XP 64-bit? If so, OC 2.0 supports XP 32-bit and Vista 32 or 64-bit, but I don't think the current version supports XP 64-bit. Do you have at least 256MB RAM?
To install on a second machine, you do not use your instillation disk. You use your Windows Live ID (must be same one you used to start a subscription). Installations on the second or third machine are based on an existing subscription. You only need to use your instillation disk when you initially install the product on the first machine (to start a subscription). OC is not a stand-alone product in the sense that a disk cannot be used for subsequent cold installs. Since updates are automated, and not manually downloaded, in theory every new install (AV, firewall, and spyware defs) could be different. By tying each download to an existing subcription, you are assured of having the most current definitions on each machine, rather than having to manually download updates for each machine (as with Norton LiveUpdate).
Look for install instructions for second and third machines here.
http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2974382&SiteID=2
Hope this helps
