No sound after rebuild

Hi guys

I'm having trouble getting sound from my A7V8X-MX motherboard. I've just rebuilt my machine using WindowsXP professional and for some reason ther is now no sound coming from my p.c. All connections are intact. I don't know if I need an audio driver or if I need to update my bios. Please help it's really getting annoying now, it's been more than a week and I'm lost without the sound.