Check sound configuration in some places, so that the channels are correctly config'ed (often '2.0' or 'stereo' if you're using the laptop's built in speakers or headphones, and corresponding options if you're using a home cinema system or similar), and also check that the sound output you're using (can be 'analogue' or 'digital' and some variants of those) is the primary and default. This is done in the control panel -> sound. (At least on Windows Vista and later, check the Internet for more detail on how to make sure that the output you're using is the primary)

You can also check the sound acceleration and sample rate levels, however I've no direct info on how to do that on Vista, unfortunately. (Know how to do it on XP and W7 though ^^) Check the Internet again

Also, driver settings can be important, see if you have some icon in the taskbar to control sound settings. Turn off any environmental effects, sound enhancements etc. etc. as these may effect certain applications producing sound.

Last, check the SoaSE ingame setting, tinker around with any that can effect the sound output (there are quite some there, so see if anything makes a difference and make notes of which affected the sound in which way to nail the problem better).

Hope some of these advices might help, other than that I can't give much except looking around the forums for more help on the issue