No Sound on XP


I've recently installed XP on my W7 PC, it now dual boot beautifully with with EasyBCD 2.1 but I can't get any sound when I boot to XP (the motherboard is ASUS P7P55D-E LX) - XP reports that it can't find a sound card. Has anyone come across this and fixed it cos i've run out of ideas? Thanks
Moved to Windows Support. Not related to EasyBCD as it is a question about missing drivers.