AUDIO & VIDEO DRIVERS FOR DELL INSPIRON 6400

Dear Friends,

I have installed Microsoft XP Professional recently on my Dell Inspiron 6400 Laptop and I can't able to install correct Audio and Video drivers.  I tried Sigma Tel Audio driver from support.dell.com but, it is not working.  Even I can't able to play any videos.  I think it may be because of my display drivers.   Can any body help me where I can get exact drivers and any settings I need to change.  I can able to connect to Internet.

Thanks in Advance,

Shrik.