Yay you, and yay for not waiting! I agree with what the others have said; panniers, fenders, and all the lights. Pre-loading your work clothes also sounds like a good idea; the less you have to carry, the better. As far as cold weather clothing goes, I find layers work the best. Have fun working out your route; I love seeing new places.

And have fun! Make your co-workers jelli when they see your big stupid grin. (I may be projecting, as I get a big stupid grin when I ride.)

And keep us updated on your progress. I, for one, love seeing others' rides.