Hi henessey,
Are u sure yr. decoder can detect the DTS signal from yr. PC?
I experienced a problem for detecting DTS signals from PC (similar config. to yrs PC and tried yr. method already)
I am using Yamaha VS-10: (http://www.yamaha.com/yec/cavit/products/pd_VS10_01.htm )
and u?
Nice to meet U here!

My PC:
Dual P3-1G on Abit VP6
1G PC 143 Sdram
Raid 0 90G HD (IDE)
Matrox G400 Max
Pioneer 16X DVD
SB live with Speed I/O card
Optical cable X 1
s/w
Win2000Pro ChineseSP2
Power DVD XP
Win DVD DTS ver.
DVD genie 4.05