You can install a virtual machine and install most any OS you choose. From DOS, to Windows 3.1, Android, Linux, etc.
I use the Oracle virtualbox which is very easy to install, and is free to use.
www.virtualbox.org
Anything in "Startup"? Just delete anything there that you don't want starting with the machine.
Get Ccleaner and run a registry check.
https://www.piriform.com/ccleaner/download