Vista ultimate has all the features of all the other versions of vista. I would recommend the ultimate version even if the advisor says you don't need it. The advisor asks some basic questions and then just recommends a version based on what windows thinks you will be using the computer for. My PC has lower specs than that and it runs vista perfectly, so it isn't a case of his specs. Ultimate has features like Media Center, Windows DVD Maker and others that aren't on the home basic edition.

With beta 2 you could download different versions. with RC1 the code for all the versions is on the same DVD. If you like you can install without a product key. after you confirm you don't want to enter a product key you will be prompted to select what version you want to install. select whatever you want. the only downside is that it will only run for 14 days then you have to do a clean install or enter a valid license key, which by default will be for vista ultimate

hope that helps