You can point to the Poser 7 runtime. Just be advised that if you run Windows Vista/7/8 that UAC will apply, so do not install content to your Poser runtime if you have UAC turned on. During the install it will create a content runtime in your Documents folder.

You can either move the Poser 7 runtime or leave it where it is if you think you may still want to use it from time to time. Poser 9 will not overwrite your Poser 7 install. You can point to it where ever it is.

Laurie