SPDIF passthrough in Windows Media?

[Freo]

Is there a way to enable spdif passthrough in Windows Media (I'm using 6.4 but will upgrade if it means I can use this feature) so that my receiver can decode the AC3 sound? I can do spdif passthrough in BSPlayer but the video is too choppy with this player. Would rather use Windows Media. Any suggestions? Thanks.

Sound Card - SB Live! (non 5.1)
AC3 Drivers - Intervideo