Missing network, sound after XP installation on DELL optiplex GX260

After XP installation on my Dell optiplex GX260, I got two critical problems.
first, network connection is failed so I am unable to set up workgroup for all my computers to share together. Secondly, sound is missing although everything is OK if I check sound  device hardware.

Following is the solution. Please remember my machine is Dell optiplex Gx260. I  am not sure if it is OK for another Dell. But try it first.


For nerwork:

Download and run Dell driver: R54402

For Sound:

Download and run Dell Driver: R56339