Solaris by default sets the line output muted and the internal speaker active for sound. Your soundcard is probably working fine except that the line output is off, so have a look at the settings in the volume control (mute master mono, and unmute master stereo)
The video card is a bit more difficult, but still relatively straightforward to correct ( only type the bits in bold face)
# init 0
ok {} show-displays
a) /pci@1f,0/SUNW,m64B@13
b) /pci@8,700000/SUNW,XVR-1200@1
q) NO SELECTION
Enter Selection, q to quit: b (this is my xvr-1200)
You will then see:
/pci@8,700000/SUNW,XVR-1200@1 has been selected.
Type ^Y ( Control-Y ) to insert it in the command line.
e.g. ok nvalias mydev ^Y
for creating devalias mydev for /pci@8,700000/SUNW,XVR-1200@1
then enter:
ok {} nvalias screen ^Y (control+y)
ok {} reset-all
The sound card I was able to switch over with stdaudiocontrol, I was only able to figure out the video card using the advice reborg gave me... well that and physically removing the card I didnt want in after doing a touch ./reconfigure