I dont know which drivers to be installed for audio .

Hi deepakbandi,
the model number you have listed is not 100% correct. If you found another site that shows two audio drivers, please list the link here in this post.
Or goto this VIA link & match the model number to the motherboard picture.
http://support.octek.com.au/Products/MainBoards/P4/VIA/mb_p4_v_08.htm

As you will see, P4M-266 is part of the model number. 8233 is part of the chipset.
VT8233 chipset. P4M266A-A4E Pentium 4 Main Board. There are two On Board Audio AC97 Drivers.
Download & install 2 channel audio (VT8233): http://support.octek.com.au/Update/VIA/V823x.htm

Good luck!
Mike