Opening PAK files for Retro Games Thread

I've obtained a few of the old retro arcade games, such as Donkey Kong, BurgerTime, DigDug, and want to try my hand at making a mod for them or to update. I have found source code for some of them, but the asset files are in .pak files. I've googled to find software to open them, but the suggested ones (WinZip, WinRar, etc.) don't work. Does anyone have any suggestions on how I can open the files so I can work with the graphics, sound, etc files?

Thanks!

There has been a very good and simple to us software, but it was made for HL1 so I don't know if it would work with your games.

This is a newer one I found, post if it works for you:
sourceforge.net/projects/dragonunpacker/

Edited by: Reborn:X

You have to find out how the content was stored. .pak was an extension id made up for Quake 1/2 engine games. Q3A used "pk3" & D3 used "pk4", both renames of .zip, so those would open in a zip program.

But the key is finding out how they're stored, the extension is pretty much meaningless.