Vista - no audio after installing windows vista

I installed windows vista on my HP pavilion a1600n... i lost ALL sound
comming out from my speakers. I turn my speakers to full blast all i hear is
static, but in the background i have itunes playing. it doesnt stop there the
regular application sounds wont play even when browsing windows. I've updated
the drivers, it's compatible and everything. My speakers aren't on mute. i
checked the BIOS and put the audio option on 'enabled'. I went to hp and did
all their troubleshooting suggestions and i still have nothing. When i go
under properties windows says that the driver is functioning properly. I
checked the vista website for compatibility and my audio driver (Realtek
Audio HD) is listed as compatible. All audio was working fine when i was
running on XP.

is there anyone out there that can help me?