TechwareLabs has published a guide to the difference between Onboard and add-on sound cards.
>> Why buy an Add-on Sound Card?
With the widespread availability of onboard sound why would a consumer select an add-on sound card to their system? We take a look at the actual difference between onboard and add-on and give you insight as to the technical differences and important features to look at before making this decision.
>> Why buy an Add-on Sound Card?