Here's an idea: Install Linux.
I recommend using a virtual machine such as VirtualBox, which can run on a normal Windows box, to install a popular, well-maintained and lightweight system such as LubuntuLubuntu or Bodhi. Using a virtual machine means that you can run it as an app on your Windows computer; and this method will shield both the host and guest machines from malware that the ancient IE5 might pick up.
On the Linux machine, install PlayOnLinux (from the standard repositories — for full compatibility, don't download it from the website). PlayOnLinux has a built-in method to install legacy Internet Explorer 5 or 5.5. If there is data that IE5 needs to share with the host machine, you can set up a shared folder on the host machine for this.
Once set up, you can save the virtual machine and then copy it to other Windows boxes as required, without having to set up each machine individually.
Although it takes more initial setup (it shouldn't take an experienced Linux user more than a couple of hours on a modern Windows box), it's a safe and portable solution.