NaNoWriMo, and the Curse of Two Entirely Different Things I'd Like To Write

I decided what I was going to do this year several months before, and managed to mostly keep the inspiration in check and gradually building up... but now, with only a few days to go, something else has infringed. Something that's coming on strongly to me right now, but with very little build-up to it. Something that I'm certain will interfere with my performance if I stick to the original plan... but if I switch gears and write this new thing instead, I'm certain I can't keep up with it. I don't even know where it would go after the beginning points.

Sometimes I feel like that one author in Sandman, that gets more ideas than he can handle and is driven mad by it. And I didn't even get to sleep with a muse for it!