How can I automate sound device selection? (speakers vs. dock)

Hi, I have a VAIO laptop which has 2 sound devices shown:

1. Speakers / Headphones (SigmaTel HD Audio CODEC)
2. Digital Output Device S/PDIF (SigmaTel HD Audio CODEC)

This is pretty simple - when the laptop is undocked I want it to use its
spakers (1). When it is docked I want it to use the docking station's
S/PDIF (2).

Yet at the moment I have to manually go into Control Panel > Sound, select
the device each time I dock/undock, and click Set Default.

Surely there is an easier way? I'm sure XP used to at least attempt to
switch automatically.
--
Thanks,
CJSnet

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