No, uninstall the game by using the uninstaller. After that was done succesfull manually remove the Bohemia Interactive folder. You can find that folder where you first installed the game.
Than reboot, put the DVD in your drive, install Arma 2, install Arma 2: OA (install it inside your Arma 2 folder, it should find that location automatically), install Arma 2: BAF, install Arma 2: PMC.
Than start the game and check which is your game version (lower right side of the main menu). I think the anniversary version is 1.59 but I am not sure about that.
Than, apply patch 1.60 (see the patching guide I linked you to above) and start the game again. Try to join a MP game.
If you still recieve the battleye error you may have to manually install battleye:
(make sure to download/install correct version)