Upgrade to Linux. Run Windows 7 in a QEMU VM (allows more direct hardware access to videocard VirtualBox). Clone box for each program you want to run. Only one run VM at a time.

Thus, each program is completely sandboxed, and more secure than windows 10 will ever be, even with security updates: Only vulnerabilities will be those in the specific programs which should be getting updates. And your hardware is protected by Linux, which is getting updates.

That said, Windows 10 IS a security hole. Despite all the bad advise on here telling you to do so, side-grading to Windows 10 doesn't make you more secure; it just makes you insecure to different things.

Here's the experiment I ran, if you feel tech-savvy, I suggest you run it too, and not just take my word for it. 

I ran a comparative analysis between Win 7 and Win 10 across a DDWRT router that I had sniffing packets on my network (white hat of course). With 100% of Win 10's options adjusted to favor privacy, and Win 7 running stock install, Win 10 had literally nearly twenty times as much data being dumped to the internet while just sitting there than the Win 7 box did by active browsing. All that Win10 data was just waiting to be sniffed, catalogued, advertised on, etc., the vast majority of it going to IPs designated in blocks registered to Microsoft or the US Military (that second one surprised me a bit). Further, blacklisting those IPs on the router... the Windows 7 machine ran fine, but the Windows 10 machine then refused to connect to the internet at all afterwards. 

Whatever security you may think you're getting switching to Win10, you'll lose equal measure in different types switching to Win10. 

However, between un-updating Win7 and updating Win10, I guess in the end it all boils down to which government you want having your data more... the Chinese government or the US government+Microsoft.