Dealing with PC Sales People
There are many good salesmen out there and most will try and do the right thing by you.

That being said, they are salesmen, and their job is to sell, not inform. In places like Harvey Norman and Radio Rentals, they are often school leavers in their first job and or have very limited understanding of the technology they are selling. They say yes to the questions they don't understand in the hope that it will all just work out in the end, not out of greed for commission, but because they don't want to look foolish in front of you.

If you are buying a notebook for your children's homework etc, then there is nothing wrong with buying at these sorts of places.

If you run a business, even a one or two computer setup and you are not well versed in computers, its worth seeking professional advice.