12" powerbook case?

I am looking for a case for my 12" powerbook. I will be attending MBA school this fall, so preferably something that would be ideal for school.

So far the best thing I have seen is Apple Computer Incase Laptop Sleeve - Carrying Case. What do you guys use?

I found the sticky thread on cases. However, there are SO MANY options. Which ones do you prefer?

I am not sure what would be practical for carrying it around to classes. Maybe just a sleeve that I could put inside a backpack. I don't really know...