The Virtual instrument uses the Digital to Analogue (D/A) converter in your sound card to convert its sound, it does not use any of the sounds built in to your onboard soundcard.
I would recommend you obtain an external Fire wire or USB 2 sound card, as most laptop D/A converters (Including Sony) are of very poor quality.
BTW You may like to post on the SZ Software arranger forum, as others have already done what you are trying to do.
Hope this helps

Bill