HOW do I unroot if I want to eventually take one of the OTA updates that might come in the future? (I'm NOT interested in 4.3 at this time).

I found this: Official VRAMC3 4.1.2 5/5/13-
This is the latest firmware image that will return your device to factory stock and locked conditions.

at the xda site. is that the item needed, or is there some other process to unroot?