well, i dunno if they make that 'smart' onboard audio setup for laptops where u can put in anythn, and then configure accordingly... like my mobo's got an onboard soundmax weird thing... i dun really use the onboard audio newayz...
gettin back to ur problem, well, its simple... get a stereo splitter... its probably gonna reduce the sound quality, but then, it works....
here's what it looks like:
*www.cablesforless.com/ProductImages/items/AUD-3000.jpg
but then, it is kinda weird that an audigy card in ur laptop duznt support 5.1 sound... :S
check ur laptop manual... i tried googling a bit for ur laptop wid an audigy, cudnt find nuthn relevant...