i recently upgraded my os with win xp pro from win xp home edition . every thing works fine except it doensn't play any sounds i downloaded latest drivers and installed them but it doesnt work. my system details are
gigabyte 945 mother board
core 2 duo processor
geforce graphic card 7200 series
pls help me

Have you tried the audio troubleshooting steps on the Gigabyte support page?

Do you have Windows Service Pack 2 installed?

If yes, post the exact model that you have of the 945, there are 9 model versions and revisions.

A troubleshooting example for the GA-945GCM-S2 (if that is what you have) is located here.