The thing about these Virtual PC programs is that the sound is emulated and the actual drivers for the SB Live won't work, so you need to find out what drivers will work.

To quote from the manual:
Virtual PC provides 16-bit, 44-kHz sound input through Sound Blaster 16 emulation. This means that you can use a microphone to record sound directly into PC sound applications running on a guest PC.
Component Guest PC emulated hardware
BIOS.............AMI BIOS
Chipset..........Intel 440BX
Sound Card.....Creative Labs Sound Blaster 16 ISA
Network Card...DEC or Intel 21140 10/100
Video Card.......S3 Trio 32/64 PCI with 8MB VRAM
Sound
  • Emulates Creative Labs ISA Sound Blaster 16 card
  • Supports both DSP (sound effects) and FM synthesis (music)
  • Emulation includes two Yamaha OPL2 chips as well as a CT1345 mixer
  • Sound card is configured to use a base port of 0x220, IRQ 5, and DMA channel 1 (for 8 bit) or 5 (for 16 bit)
  • Supports 8-bit and 16-bit sound input and output
You may not even need drivers for dos, all you need to do is configure the game to use the above settings