My settup Apache 2 PHP5 and Mysql 3.2.3 SLES 9. When I attempt to run install.php I get the following outpu in my browser. I have Apache/2.0.54 (Unix) PHP/5.1.0 mod_chroot/0.3 mod_perl/2.0.2 Perl/v5.8.3 configured and running and I have an empty error log file.
Can't do the specifics, I'm afraid, but a few thoughts. It looks as if your are displaying the contents of a file which chould be executed as PHP. Could be that install.php is corrupted in some way.
If its a new web server installation, you could do a partial check by just uploading a few plain HTML pages and seeing if they display.
That's also quite an old version of mySQL - I know its nominally within the supported range, but sometimes things unintentionally creep into the code which require a newer version.