CompUSA had the worst salespeople. All they could do was read the card listing the specs for you.
Amen on CompUSA. They also had huge disdain in my experience for their customers. When I returned 3 memory sticks in a row that did not work, they were very obvious in questioning my ability to operate a computer (when I knew more about the problem than they did). I also had problems in the store with salespeople apparently assuming because I was female I was an absolute idiot regarding computers.