My experience with OneCare was this:
I didn't like it because it kept popping up saying I need to back up, among other things the firewall is not that configurable (it's almost just like the windows firewall with outbound protection tacked on). I go to uninstall it, and it has issues uninstalling - but magically removes itself. Except, it kept all the ports blocked on my computer and of course since the program was uninstalled I had no access to blocking/unblocking them - so I couldn't use a lot of different programs. Eventually I had to do a system restore, back to when I had norton installed, and norton was totally screwed up by the system restore and took about 200 clicks of "ignore the fact that you can't find ccsomething.exe" and about 20 cups of coffee.
My recommendation is NOT to install OneCare.