property newName : 0
set theFolder to (choose folder with prompt "Choose Folder" with invisibles)

tell application "Finder"
    set theFolders to folders of theFolder
    set sortedFolders to sort theFolders by name
    repeat with i from 1 to count of sortedFolders
        set newName to newName + 1
        set thisItem to item i of sortedFolders
        set name of thisItem to newName
    end repeat
end tell