+1 to the sugestions to have a "beater" for campus. I second Sixty Fiver's recommendation to find a basic 1980's road bike and make sure it is all tuned and ready to ride. It will be far more pleasant than your current bike and won't attract too much attention.

If your commute was 1-2 miles, I'd say stick with the Wal-Mart POS. For 6-8 miles, I'd be pining for something more pleasant to ride.

Then, save money on the side for a nice road bike for your longer weekend rides (and who knows, club rides during the week).