The AgTalk-approved answer is: Don't upgrade from Windows 7 to Windows 10.

New computers that ship with Win 10 installed usually run just fine. Your biggest worry is a forced update that introduces more bugs than it fixes. But Win 10 upgrades have been fraught with peril, with some making the jump alright while others have experienced no end of trouble. Especially on an older machine, it simply isn't worth the risk.

So, start gathering specs for a new computer and go get yourself something nice. Install the software you need, then work on migrating your data over to the new machine.

When you're finished, you can do what you like with your old Win 7 computer. There are ways that you can still get a free upgrade to Win 10, if you want to chance it. Or you can continue to use it offline. Or you can install the Linux distribution of you choice on it and do about anything you want, while marveling at its newfound speed and stability.