I use Win7 Ultimate as well. On my system, I unzip the entire contents into Computer > OS (C:) > Users > MyUserName > My Documents > DAZ 3D > Studio > My Library, and I make sure to MERGE the folders. Be advised that some files and documents are duplicated in 2 different zip files for a product. For example, clothing or characters that are for both G3 and G8 have some duplicate files which can simply be replaced by the duplicate. The reason for this is some might want to only install only one of the versions, and avoids having to cherry pick through the files and manually install the necessary files for only a single version. Template files do not need to be installed or downloaded if you're not going to make your own custom textures/add-ons for a product.

I was lucky when it came to learning how to install stuff from renderosity. If I screwed something up, I could just reboot and try again. If I got it right, I just unfreeze my drive and repeat the installation.