Win 7 backup is more of a backup solution than a synchronization solution. It allows you to select files and settings and then it backs them up to a single file that can be restored later. It also can store incremental backups, and I believe you can have multiple points in time in a single backup. If you are looking for a backup solution, then it is good. SyncToy is more of a synchronization tool, that makes folder a match folder b.
If you want to access your files from both locations, SyncToy. If you want quick restoration of a system, then I would use Backup.