7z files don't need winrar, or winzip or 7 zip, they are prepared for obmm already, just go into the obmm, click the create button on the bottom right, it will open a new window and and in the middle it will have three buttons: load files, load folder and load archive, click load archive, then navigate to where you downloaded the file, load it up, and then it will have a place to name the mod at the top left, put its name there, you don't really need the description or author if you know where you got the mod, then click the create omod button and it will start up. once it finishes double click the mod with the green square next to it on the right, it will ask you if you want to activate, yes, then start the game, no need to check data files, already done. EDIT: btw, i'm using vista and windows 7, (not too many problems with 7, none with vista). if you need help with the run as administrator stuff let me know, i could walk you through it.