Even better, get a Firewire or USB drive. They're more robust, smaller, and lighter. Put your data on them, and take it back and forth between home and work. Your laptop will looove you, and if you're like me, your desktop PC at home can dominate the laptop every day of the week. Plus, multiple copies of your data on 2-3 different computers means redundancy. Big win there.

I tried taking my laptop with me in panniers and a saddle bag, but it just wouldn't stand up to it despite a short 1.5 mile commute. And I'm pretty easy on my gear.