Modern Warfare 2 Zombie Maps

In Vista: To add Zombie Maps to MW2
C:\Users\YOUR_PROFILE\AppData\Local\Activision\CoDWaW\mods\

Double Click My Computer

Click your computer name - usually your name
Click AppData
Click Local
Click Activivion
Click CoDWaW

It should then show the following folders, mods, players and usermaps, then extract the maps into the mods folders

If there is no mods folder you will have to create one in there but make sure you use all lower case letters. When you download the zombie map you will need a zip program like winzip or winrar or whatever you use. So after the download finishes it should give you the option to open it, so click open and then extract it into the above folder and thats all there is to it.

If you are running XP then go to:
C:\Documents and Settings\YOUR_PROFILE\Local Settings\Application Data\Activision\CoDWaW\mods\