Thanks for answers guys. I also forgot to mention that I live the Pacific Northwest and it rains pretty often here, so the fender is a must here.

"So, is it possible to squeeze more cash out for your new bicycle?"

I can. I went looking for the 300 since it seems like the cheapest price for a road bike. What price do you think I will be looking at?

"Also factor in the price of a proper backpack or pannier to protect your laptop. And a plug for my humble commuter blog. I wrote there about different kinds of bikes, how to prepare for your commute, how to keep safe on the road, etc. A few people found that helpful, perhaps you will too. "

Thanks for the info. I'll probably look into getting a pannier.

"For a 4 mile commute you're a good candidate for a messenger bag, since sweat won't be profuse and comfort will likely be good."

I've done a test run on an old used road bike and I sweat a lot from it since it was mostly an uphill climb to work.