Hmm...no reason for XP compatability, as the drivers are fully Vista compliant. (Heck, thats probably the reason for the crash).
Re-install the driver package, making sure NEVER to use compatability mode for anything driver related. Remember to use the 64-bit version if you use 64-bit Vista.
On a side note: Theres no reason why 2 speakers won't output to the headphones if the headphones are plugged in properly (sound may not be optimized for headphone use, but a good tool for testing purposes).