Wouldn't bother with Windows 7 - unless it's an offline PC used for Gaming.
Instead, i would recommend something like Linux Mint (begginers friendly). Comes in 3 flavor - and for your particular PC (older) - either
Linux Mint "Mate Eidition" or "Xfce Edition"
...would be ideal. Point being - both are quite light in terms of System Requirement (so they feel and move really fast and smooth - as if your old laptop was made for them). Also, they're regularity updated
- so it's kinda like having the latest version of Windows. Just give it a try - usually takes around a week to get used to it
. Not to mention - similar to Windows Linux Mint gained a lot of popularity in past decade or so - thus , there's tones of support for any issue you might encounter.