Thanks babe!!Can you not use your brain for more than 5 seconds at a time? Yes of course it is if it says so in every server title, and the latest version on the mediafire repository is 1.4.4, development versions are never "visible" to the public unless it's noted down as such on the mediafire.
Make sure you have the latest versions of ALL THE FILES on the mediafire repository.
Go to your arma2 oa folder, make a new folder in it called @DayZ, inside that folder make a folder named "Addons", now all those zip files you downloaded. Extract the contents of the zip files into the addons folder inside the @DayZ folder you just created.(pbo files and accompanying .bisign files.)
Now if you know how to launch the game with modfolders which is by doing -mod=@DayZ; you'll be set.
If you have arma2 combined operations on steam simply right click arma2 oa in the games list and find properties on the right click list for the game, when that window is open go to launch properties and put -mod=@DayZ; there.