No Audio Device after Reformat?

I just recently re-installed windows on one of my friends computers, I was hooking up the speakers and I noticed there was no sound, I check and there is no audio device detected? They don't have internet access and I can't download the drivers directly to their computer so I will be going back with the driver on a USB. Does anyone know which drivers I need to download? It's a Dell Dimension e521, the spec's say it has a Sound Blaster X-Fi ExtremeMusic with Dolby 5.1 integrated 7.1 Channel audio. I'm not quite sure which Driver to download, so any help or points in the right direction would be greatly appreciated.