I want to download Zend Optimizer but I don't know which version should I use. By the way is this utility good?

My server info
PHP Version : 4.0.3pl1
Apache Version : Apache/1.3.14

Types of Zend Optimizer

FreeBSD 3.4 (for PHP 4.0.4)

Windows NT/2K (for PHP 4.0.4)

Solaris Sparc (for PHP 4.0.4)

Linux glibc2.1 (for PHP 4.0.4)

Linux libc5 (for PHP 4.0.4)

FreeBSD 4.0 (for PHP 4.0.4)

Windows NT/2K (for PHP 4.0.3)

Solaris Sparc (for PHP 4.0.3)

Linux libc5 (for PHP 4.0.3)

Linux glibc2.1 (for PHP 4.0.3)

FreeBSD 4.0 (for PHP 4.0.3)

FreeBSD 3.4 (for PHP 4.0.3)

Windows NT/2K (for PHP 4.0.5/4.0.6)

Solaris Sparc (for PHP 4.0.5/4.0.6)

Linux libc5 (for PHP 4.0.5/4.0.6)

Linux glibc2.1 (for PHP 4.0.5/4.0.6)

FreeBSD 4.0 (for PHP 4.0.5/4.0.6)

FreeBSD 3.4 (for PHP 4.0.5/4.0.6)

Which operating system do you use?

RedHat 7.1

The "Linux glibc2.1 (for PHP 4.0.3)" one should work, then.