go into add/remove programs and uninstall the drivers for the soundcard. don't restart yet. Then right click on my computer and slect properties. Go to the device manager tab and go to the sound, video and game controllers line.
Click on the plus sign to exapnd it. right click the relevant lines to you soundcard and uninstall them from you system. Once this is then shutdown the pc.
Unplug the tower from the wall and Get an antistatic strap and connect it from your wrist to the metal casing of your tower.unscrew the screw that holds in your soundcard and then gently but firmly pull the card out from the pci slot on you motherboard. It may have a cable attached to it running from a cd drive. This is to provide cd audio playback if you play cds through you pc. unhook the cable and kep it ready to connect into the new sound card.
Now put the new sound card into the same slot you took the old soundcard from. If you have xp this should be fine. If using an older operating system it might be better to put it into another pci slot which has always been unused, this is to prevent irq conflicts.
When putting the new card in make sure you don't touch any of the gold contacts at the bootm of the card which will fit into the pci slot. Also make sure that it is fitted perfectly into the slot and you cant see the gold contacts once it is installed.
Then connect the audio cable back up to the sound card, (if necessary) and replace the retaining screw to keep the new pci soundcard in place. Put the case back on and connect the pc back up. Turn it on and go straight into the bios (keep pressing delete). Make sure that it is Plug and play aware (PnP = Yes) then save this and reboot. Now let the pc boot up and it should prompt you to install sound drivers.
Just place the cdrom in the drive that came with your sound card and then just follow the instructions.
Then reboot when it is doen.
Hope it helps.