I just purchased SoundTap and had this same problem. I don't know if you recently purchased the software, but make sure you have v1.4- this version works with Vista. Once you have the current version, here is the other problem you have to fix (I copied this from another thread in this forum- I never would have figured it out myself):
As a Vista security measure, driver signature enforcement is enabled every time you start your computer. To correctly install SoundTap driver for Vista do the following:
Restart the computer
Repeatedly press the F8 key
Select "Disable Driver Signature Enforcement"
Windows will now boot up
I just did this and successfully recorded an internet stream.