Right click on the My Computer icon on your desktop and go to Properties. Go to the 2nd tab and click Device Manager. Once it opens look for any devices with the yellow exclamation mark. If you see one on your sound card it may not be broken only as Lurker said in need of a driver.
If so Right click on the exclamation mark and do the Update Driver. Hopefully it should go out and find the driver.
They do make a USB(external) sound card.
eBay: Creative Soundblaster Extigy - USB External Sound Card (item 220071277601 end time Jan-20-07 04:14:41 PST)