There is no such a thing as Poser 7 Pro, it is straight PoserPro.

GI does not exist in P7's render settings, you will need to fake it with IBL lighting to an extent, although IBL works best with outdoor scenes.  BB's envsphere can provide exterior lighting based on a self illuminating skydome, and perhaps creating an IBL image for your interior lighting might give you a more exacting result.

Both can be found here:

http://sites.google.com/site/bagginsbill/free-stuff/environment-sphere

http://sites.google.com/site/bagginsbill/free-stuff/genibl---ibl-generator

BTW, GI currently exists in P8 and PP2010