According to Creative, the Audigy is basically an improvement of the SBLive! If your Audigy card has soundfont compatability, then that SBLive! patch should work fine with your card. I don't understand why it is called a SBLive! Patch because what is included is just some soundfonts. You'll have to ask the author (Taightondude, is it?) for full information on that.
..and YES it should and will work in Windows XP. There are other topics that have explained how to correctly set it up in XP..but I'll just rephrase their divine knowledge.
Follow the directions on installing the SBLive! patch (ie. where to put it) and in your ff7 setup set your midi data to MIDI Soundfont AWE32/64
and your Midi driver to your default soundfont output device. I don't know the specs for the Audigy, but on the SBLive! the output device is - A: SBLive! Midi Synth
Hope this helps.