Open OneCare on the new PC, select Restore Files and then select to restore from another computer. Provide the location of the backup files. Note that the backup needs to reside on the same media to which it was backed up - an external USB disk on PC1 needs to be an external USB disk on PC2 in order to restore from that disk, fr example.
If the backup is not recognized by the new OneCare on the new PC, you can configure a backup plan on the new PC to perform a new backup to the same location as the old backups. For the "what" option, select a small set of files, say Financial files, for example, then perform the backup. Once it has completed, use the restore function as above.
If you need further help, check Instant Help for the backup and restore topics or contact support:
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
-steve