Final answer:
The Microsoft Windows Memory Diagnostic Tool is the preferred RAM diagnostic tool for systems predating Windows 7. Alternatives include Memtest86 and Memtest86+, which are bootable from external media.
Step-by-step explanation:
The correct RAM diagnostic tool for diagnosing RAM issues in computers running operating systems prior to Windows 7 is the Memory Diagnostic Tool provided by the Microsoft Windows operating system. For systems that predate Windows 7, users would typically rely on the built-in tool, accessible by pressing F8 during startup and selecting the option to run the Windows Memory Diagnostic. In the event that this utility is not accessible, you may also use third-party diagnostic tools such as Memtest86 or Memtest86+, which can be run from a bootable CD or USB drive. These tools are designed to test and diagnose problems with Random Access Memory (RAM).