pihwht,
Don't be in a hurry to buy.Do some research first, there is plenty of information available on this forum and others. My neighbor, who has just gotten back into biking, started with a used mtn bike, switched to a trek 7200 hybrid, and is talking about a road bike for next season. This all in about a 2 month period. He was of the same mind as you-bike to work and back and run some errands. Now he's hooked and is talking of longer rides and (god forbid) goal setting for yearly mileage etc.. Of course now that you mention a new bike, it would not be such a bad idea and at my current weekly rate I should be able to hit.....
rck