http://support.asus.com/download/download.aspx?SLanguage=en-us
I can't link to it because idk hard to explain lol link won't work. But go to the search box on the left of the page and just type in P5k SE, your motherboard should pop up in the results, only the P5K popped up when i searched, then click that, it will show you drop down lists of every driver ( LAN, AUDIO, VIDEO, ETC.) pick your OS and everything download it and it should give you instructions how to install.
EDIT: Make sure you get the 32-bit version if you have a 32-bit OS, and 64-bit if you have a 64-bit OS.
I can't link to it because idk hard to explain lol link won't work. But go to the search box on the left of the page and just type in P5k SE, your motherboard should pop up in the results, only the P5K popped up when i searched, then click that, it will show you drop down lists of every driver ( LAN, AUDIO, VIDEO, ETC.) pick your OS and everything download it and it should give you instructions how to install.
EDIT: Make sure you get the 32-bit version if you have a 32-bit OS, and 64-bit if you have a 64-bit OS.