If you can’t upgrade the donated laptop past Windows 7, you need to be looking into what was current during its time.

I can only speak to my experience, but of all the sequencers/DAW’s I have used, I found Cubase the best at dealing with MIDI. Other DAW’s handled audio more conveniently for certain, and every DAW has something unique and possibly useful, but I found Cubase presented the MIDI in a visually clear system of editors.

Frequently used functions like selecting a specific range of pitches inside a specified window (position in the bar, velocity window or degree of proximity to the grid e.g.) were easy to accomplish. This makes tasks like evening out a backbeat snare or selecting ONLY notes a set distance away from perfect (and leaving those ‘close enough’ alone) to be quantized etc. a much faster task than say ProTools or Logic.

It also had the advantage of being cross platform, so if you wanted to migrate from Windows to MacOS (or Vice versa!) you didn’t have to learn a totally different DAW.

But that’s just me. Everybody has their own workflow that might be better served by Ableton Live, or Reaper or Fruity Loops or Logic etc..

If you like working with audio loops, or composing EDM tracker style music, or want to do acid house and trance, each style of composing has its own fans with favorite features. It’s not an easy choice, and the wrong one can easily cause frustration!

Take your time, do your research. An OS as old as Win7 may give you its own set of challenges trying to get old versions to authorize.

Best of luck!