hey wadddup,wahts the best program to open .pk4 files?i tried to get quark btu it wouldnt download.

I am pretty sure you just rename the pk4 to .zip and unzip the file

Layzmon is correct, pk4 is just a compressed file with the same file structure as a zip file. You can rename them .zip and unzip them or http://doom3.filefront.com/file/PK4Scape;31661 which is a utility designed to handle PK4 files.

By the way, if you're looking for a Mod, here's a great one (and the install guide is real easy to understand too ^_^):

http://ibeatgodzilla.wordpress.com/2010/12/18/tourettes-guy-doom-mod/

Based on YouTube's Tourettes Guy (doesn't actually have Tourettes' Syndrome), this mod has Danny the Marine, with a new soundtrack, hilarious lines and new pick-up and item skins!

WARNING: MOD CONTAINS STRONG LANGUAGE - PLAY AND DOWNLOAD AT YOUR OWN RISK!