I would think you should just be able to connect your IDE drive as an external and then Take Ownership of all the files on it.
If, however, you really did restrict permissions so much that only your old system's user can access them, you might try connecting the IDE HD directly to the motherboard using an IDE-to-SATA adapter and booting from it.
Mind you, booting an existing Windows system on completely new hardware carries the risk of it not starting up at all, but if it does start up then you can go about restoring access permissions for "everyone," thus allowing yourself to retrieve all the files from a new Windows installation (presumably the one on your new SATA HD).