I realize your wanting to stay with what's familiar, but 24 years is a long time.   From what I've read even Windows Vista, 7 or 10 won't run QB99 due to compatibility issues.
QuickBooks Desktop (QBDT) has a three-year lifecycle so you are far behind the latest version. You might need to contact Intuit QB support or their Data Services team to find what computer would be compatible. Or ask them which more recent version of QB might be similar to the QB99 that you're using so it's not user shock. A bigger problem would be loss of your data if something happens to your current computer. Hope you have good backups and then you'd probably need a 3rd party service to transition you to whatever newer versions of QB you choose.
Just be aware that now Quickbooks (desktop or online) is sold as an annual subscription. Sounds like your QB99 has served you well for a lot of years.

Do you still have the installation disk?  I did come across this article that addresses your concern. The very bottom shares where the guy was able to install it on a 2021 Windows 10 computer by turning off hardware acceleration.  Good luck but just be aware there's a good possibility it may not work.  
https://www.justanswer.com/accounting-software/i3mwx-running-quickbooks-99-windows-10-computer.html