Extract the files to any directory (eg: C:\Program Files\Left 4 Dead) then run "setup" and complete the installation... ~enjoy!!!
If you encounter any crashes during the games, you must: 1) enable the console (in OPTIONS- KEYBORAD/MOUSE) 2) enable cheats in the console (sv_cheats 1) 3) write "mat_queue_mode 0" in the console and submit...
PS: these fixes also works on CS:S, TF2, and L4D...
TO PLAY ONLINE: *Download Standalone v7 here: http://www.datafilehost.com/download-60efa074.html OR *Run Left 4 Dead through Steam (by adding your left4dead shortcut to a non-steam game) but this may not work if the game starts to crash... also login to your steam account and launch left 4 dead...