Oh Brokencrowe what are we gonna do with you. There should be no problems using APZ clooud evening your computer is like ten years old.
Step one us ficedula's lgp tools to extract battle.lgp to a new folder.
step two copy and paste APZ files into the extracted battle folder.
step three us lgp tools to create a new lgp from the extracted battle folder
step four rename the new lgp battle.lgp and copy paste it into the battle folder. remember to backup your original battle.lgp first.
step five make sure the new lgp is not in the virtual store on vista. Run the game it should work.