Starkeeper, the GM500 is a 500mb General Midi Wavetable (128 instruments & Drumkit). Furthermore, this wavetable is designed to work in the GigaStudio soft synth and would need to be converted to whatever synth you may be using (soundfont, kontakt, etc.). Since GM is different from XG in the kind and number of instruments and the drum instruments are arranged differenctly within the kits you would need to change the styles so that they sound properly, e.g., snare drum rather than a dog howling or something like that or a piano playing rather than a drumkit. These changes are easy to make but they are time consuming.