Windows 7 Audio Device shows red X

When I installed Windows 7 on top of XP, it seems that my audio drivers were just not found, and the audio icon appears with a big red X. I click this red X in order to see if it can solve the issue, but it does not, and returns a "hardware changes may not have been detected". Device manager shows a yellow exclamation mark for 'Audio Controller Device' and there are absolutely no drivers.

I still have the OLD XP installation as a Windows.old folder, for what it is worth. Might it contain information on said drivers? Upon further check, there is reference to some "SoundMax", but that's about all I can make out of it...