This may be useful:
https://en.wikipedia.org/wiki/List_of_free_electronics_circuit_simulators
If you don't want to use Win10/11/12, I suggest you run Linux. I recommend Ubuntu. You can put a copy on a thumb drive, but I recommend an SSD with enough space to dual boot. The SSD will be noticeably faster than your old mechanical drive and a 500G SSD is only about $35. You also need a USB-SATA adapter ~$10. Cloning your old system can be problematic and you should make a system repair CD using the windows backup. I have used the "windows repair disk to fix booting problems with disk clones several times. The repair disk has to match the 32/64, win7/10 system. Linux clones (clonezilla, gparted ) rarely successfully make bootable windows. Note than the latest versions of Ubuntu are too large for a 4.7G DVD, but it's just as well because booting from a DVD thrashes the DVD drive so using a thumb drive is a way better idea. You may have to get into your BIOS to boot from USB. You need a thumb drive ISO writing program. This is a great use for your old 8G-32G thumb drives. You ~can't buy <16G drives any more.
But cheaper win11 computers today are as fast or faster than your old win7 machine. So, I recommend spending less than $500 on a new machine. New top line machines are crazy fast but only gamers care. Check the passmark scores.
https://en.wikipedia.org/wiki/List_of_free_electronics_circuit_simulators
If you don't want to use Win10/11/12, I suggest you run Linux. I recommend Ubuntu. You can put a copy on a thumb drive, but I recommend an SSD with enough space to dual boot. The SSD will be noticeably faster than your old mechanical drive and a 500G SSD is only about $35. You also need a USB-SATA adapter ~$10. Cloning your old system can be problematic and you should make a system repair CD using the windows backup. I have used the "windows repair disk to fix booting problems with disk clones several times. The repair disk has to match the 32/64, win7/10 system. Linux clones (clonezilla, gparted ) rarely successfully make bootable windows. Note than the latest versions of Ubuntu are too large for a 4.7G DVD, but it's just as well because booting from a DVD thrashes the DVD drive so using a thumb drive is a way better idea. You may have to get into your BIOS to boot from USB. You need a thumb drive ISO writing program. This is a great use for your old 8G-32G thumb drives. You ~can't buy <16G drives any more.
But cheaper win11 computers today are as fast or faster than your old win7 machine. So, I recommend spending less than $500 on a new machine. New top line machines are crazy fast but only gamers care. Check the passmark scores.