If I remember correctly, you are using Sonar. You would have to run the VST Wrapper utility that comes with Sonar in order to have it recognize GPO as a VST instrument. When you installed GPO, you were asked if you wanted to install the VST, dxi or both (can't remember if there are others). Do you recall seeing this option? What Cakewalk's VST Wrapper does is look for where these files are and adds links to them from within Sonar.
Try running the VST Wrapper first as it will look for VSTi's installed - if you still don't find they show up in Sonar, then I would suggest contacting Gary to find out how best to install them from your GPO disks.
Dont worry. We'll all do what we can to get you up and running.