Hello, ReneeT.
If OneCare restored the files to the drive, they will either be in the same location that they were before or they will have been placed in a newly created \Restore folder off the root of the C:\ drive.
OneCare should only put the files in an alternate location if you set the new PC up with a different User name and the path to the old file location doesn't work. However, that would also have affected other files and folders if you used a different Windows login User name.
I am not an iTunes user, so I can't tell you how to reconnect the files to iTunes, but I suspect that your iTunes Library needs to be rebuilt with the songs that were restored to the drive.
I imagine that OneCare support has specific experience with this problem, so if you need help, you should feel free to contact them.
How to reach support (FAQ) - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
In the meantime, someone may pop in here to provide instructions, too.
-steve
Microsoft MVP Windows Live / Windows Live OneCare & Live Mesh Forum Moderator