Thank you Logos and DavidR.
So, if I had only 3 GB of RAM, my computer would run the same, because although it can access 4 GB, it can only use 3 GB. Tt is interesting that they will sell 4 GB without telling you this at Dell. If I am using shared RAM for Video does that decrease the 3 GB usable for the rest of the system, or will that be taken for the 4 GB that I have accessible?