I've been tossing my laptop and bag into a grocery bag style pannier, and it works just fine, no damage after three years. I have a new bike on the way (more on that in a sec) and a new routine, which will be to bike to the ymca, workout there, and then bike to work. Since I want to take the laptop off the bike and bring it into the gym where I can lock it up, I'm going to put it all in a single duffle bag.

You may be interested in checking out the bikes at http://www.bikesdirect.com/, they have decent bikes starting at $300ish. I bought mine off a gal on eBay, sprtygirl, you can check out her eBay store also.