How do i update my sound card/drivers

I made a topic here yesterday asking about graphics drivers because I have been having issues with games, I installed the new drivers but the problems persist, people have been now telling me to update my sound card/drivers
.... would that be nvidia too? I uploaded my "rig" to xfire but i dont see anything about sound drivers, there is a sound card part, but it just reads: Speakers (2- Realtek High Definition Audio)... idk what that means
Help very much appreciatd

Sound Card Drivers, Click Software then download the version for your OS.

ooooooooookaaaay.... I just downloaded the new drivers... now the game crashes every time i try to launch... (yes i downloaded the one that matches my OS)

oh, brand new problem i found... just tried to watch a review over on gametrailers...... no audio, and nothing works on youtube either.
What should i do

Manufacturer:Alienware
Processor:Intel(R) Core(TM)2 Duo CPU T9500 @ 2.60GHz (2 CPUs), ~2.6GHz
Memory:4094MB RAM
Hard Drive:306 GB
Video Card:NVIDIA GeForce 9800M GT
Monitor:Generic PnP Monitor
Sound Card:Speakers (2- Realtek High Definition Audio)Speakers/Headphones:
Keyboard:USB Root Hub
Mouse:USB Root Hub
Mouse Surface:
Operating System:Windows Vista™ Home Premium (6.0, Build 6001) Service Pack 1