Make sure that you don't already have the items. You can only buy a PC item once. If you try and buy it again then two things happen. 1. If the item is a PC item only you will get a warning that you can only pruchase the item once. 2. If the item is also available as a regular item then the cart charges you the regular price (minus discount). I almost found this out the hard way but fortunetly noticed that the prices weren't what I expected. It turned out I already had the PC item but I had forgotten about it. Eric J