What project you do doesn't really matter, I don't think. I am tackling no less than three projects I've been meaning to do this year. The main thing is just writing and getting it done. You win if you complete your project, in my mind, and if that project doesn't require 50,000 words, so be it.

I think you should do it. Then you could get that project done finally. =P

Finish my project? Oh boy. I think that'll take a lot more then 50,000 words... 

Granted that's, at the very least a duology, possibly a trilogy and with an alternate book that happens under certain conditions that happen at the end of the first story.

I may have gotten a bit ahead of myself.

Okay maybe finish the project is a little overambitious in your case. =P

Mainly, I see NaNo as a reason to do some writing. Whatever it happens to be, or whatever your goals are, that is how you win. Like, for you, maybe you just try to get a first draft of the first story together? *shrug*