LOL, i've been spending better half of the last three hours trying to instal OOO. I'm suppose to use Nexus or OMM? I've looked at all the guides, and i'm still really lost. Would anyone mind telling me how to step by step?

extract into your data folder
activate it via data files
play?

it's not that simple matter to just drag the files into the data folder especially if you installed other mods. It requires a mod manager of some sort. I would recommend Wrye Bash. Start here: http://tescosi.com/wiki/OOO_Installation_Guide. Keep in mind that the latest version is v1.35.