Is there any VOX recording software out there that will let you select which sound card you want to use? This would be for Windows Vista. Neither Xcorder or Scanrec seem to do the trick.
Scanner Recorder Pro should work just fine in Vista, and allows you to choose the sound card. I'm not sure what the last version you've tried is, but the software has come a long way from just a year ago, and is head and shoulders better than the free version. It's very feature rich now and well worth the small donation to get it.