Put Linux on your old machine and run SH3 using Wine. It works fine. And it's all free.
https://ubuntu.com/ or
https://getfedora.org/ for example.
You could put Linux on a memory stick along with Wine and SH3 , then just boot from the memory stick when you want some retro-action.
A note of caution - some of the more recent SH3 mods place heavy demands on graphics, which can result in unacceptable frame rates on old laptops with "integrated" graphics. This was always a problem with SH3 when it first came out and why I only came back to it a few years ago.