Running with a laptop?

So here's something I keep thinking about and am totally stuck on - running with a laptop.  I've been biking to work, and I've even walked the 4 miles home before (in the snow ... not by choice - the bus was stuck).  But I've never run.  Partly it's because I need my laptop - I have a bad habit and a need right now to work after we put the boys to bed (that was my deal when I started my new gig - I'd never miss dinner, and I'd get the job done).

So, anyone out there in blog land ever run with a laptop?  Here are the two I'm looking at:

Built  E-BPM-OLV Laptop Back Pack

The North Face Ion 20 Backpack

But, I'm not sure if my Thinkpad's hard drive can take it ... oh decisions decisions...