If frankjohn's suggestion doesn't work, try this.
Apparently MSI calls the MS-7312 a MSI-K9MM-V.
http://www.motherboards.cod.my/msi-k...312-p-498.html
Go here;
http://www.msi.com/index.php?func=do...1&prod_no=1104
Download and install the VIA Chipset 4in1 Drivers for your operating system. There is a download for Windows XP 32 bit and Windows XP 64 bit, make sure you download the correct driver.
Also, download the Realtek ALC SeriesAC 97 Audio Driver. Here again there is an XP 312 bit and an XP 64 bit version. Make sure you download the correct driver.
After you download the drivers, install the chipset driver 1st, then reboot. Then install the audio driver.
Drivers are easier to work with if you download them to your desktop, and install them from your desktop.