If you encounter 500 Server Error during magento install do following

Change Permissions

change the folder permission of below folder to 777

1. app/etc
2. var
3. media

change the file permission of below files to 644

1. index.php (main index file in magento root folder)
2. downloader/index.php ( otherwise if you will try to access System > Magento Connect >Magento Connect Manager (after magento installation)