Protecting php scripts from source being downloaded

Hi, im kinda new to this so be kind :) Im using mysql and php to create test databases (guestbook etc, basic stuff), but it doesnt seem so secure, people can just use a download manager to download the php files and steal the mysql passwords. Is there anyway to make it so they can see the php files through the brower but not download my homecrafted php? Ive looked through many websites and the history of this, all I could find was one post which was to encript the files (this isnt really suitable for me as I edit bits and bobs as I go along). Is there anyway I can setup access as said in the above? Or just hid the password somehow? Im using IIS 5.1. thanks tom