Haha, I'm the other way around. The screen does bad things to the quality of my writing. Plus, I can take a pencil and paper anywhere. Not so my desktop computer...
I actually have kind-of noticed this as well. When I am writing with pencil and paper, I tend to just write instead of constantly scrutinizing every single thing I type out. When I eventually transfer it to the computer, it ends up in a much sleeker form then it would have if I just typed is straight through. During the transfer process, you can add the little things that you missed and you catch a lot of your mistakes. I think it also allows for your voice to come through a bit more.
It might just be me, though.
On another note, I really wish I participated this year. Time is running a bit for me as of now, though. Next year is definitely a go, though.
EDIT: In reality, I have written a good 25k words this month, but they are either replies to other people's fiction, or just short stories. I wrote one thing that's about 15k, but, meh.
Like I said, next year is a go.