My model is similar to the above "pouring rain in a business suit" approach. I remember some James Bond movie where he infiltrates some sort of fancy party by arriving in scuba gear and a dry suit, and then peels off the dry suit to reveal a tuxedo. I have a helmet cover, a good rain jacket and pants, waterproof gloves, and Red Wing waterproof hiking boots. Just this week we had one day where it was raining and the temperature was just above freezing, that is, cool enough so I didn't get wet from perspiration inside the rain gear. It was perfect. Don't go too low-end on the gear. For carrying stuff, I use an Ortlieb messenger backpack, or sometimes the Ortlieb office bag.

If you arrive at work by bike on a couple days when it is pouring rain, you will cement your reputation as an eccentric. It's funny how people sometimes assume that if you are riding a bicycle in the rain or the cold you must be suffering.