Update...
When I handed the letter to my HR rep, she got all kinds of worried and uncomfortable looking, which I immediately took as OMGSHEKNOWS!
I just left it with her and went back to my work station.
Just before leaving for the day, I meekly popped my head back in to ask if I had freaked her out. She had me come in and close the door, and had a cracked grin on her face. She said something to the effect of That's all this was about? She apparently convinced herself I had given her a letter of resignation until she got into reading it.
Suffice to say, she has been really good to me about it. She said that she has not encountered this situation, but seems completely interested in learning about doing it right. We have a meeting Monday morning with the corporate HR manager for the area. I have put together a package inspired by the info in the wiki here that will hopefully make things continue to go smooth.
*fingers crossed*