If you have downloaded more than one map, you get the files download.php, download(1).php, ...
Put them all in a directory not too deep in the structure, open the dos box (execute cmd), go to the directory, where the files are (I hope you know the dos commands cd/ cd.. cd <directory name> ) and use the dos command
rename *.php *.zip
After that close the dos box and expand all zip files in one step. The expanded files will have the right names.
There are windows programs for renaming more than one file in one step, too. But I don't use it.