ASUS Xonar D2/PM Audio Driver V8.17.25-RC02 for Windows Vista 32/64-Bit Edition supports "latest DS3D GX & AEC features".

Came out in November, and I missed it before. Happily solves all sound difficulties with Vista, SPDIF i/o, DTS, EAX, etc.

I'd supply a link, but the ASUS site seems to have a mood of it's own...