New PC for parents and parts swap

Hello there!

My parent's computer died, and so I was planning on building one for them. They don't play games and really just use it for internet browsing, storing and viewing photos and videos.

That having been said, I was thinking I'd use this as an opportunity to upgrade my rig and offload some older components onto their machine, as I'll need to buy something regardless.

Parent's PC:

• Processor: AMD Ryzen 3 1300X - I don't plan on overclocking this (don't think there's a need nor do I have the know-how) but I'd like the processor to be future-proof for their purposes (hoping this computer will last ~10 years, which they typically do in this family).

• Motherboard: ASRock AB350M Micro ATX AM4 Motherboard - I know nothing about motherboards, aside from the fact I'll need a micro one to fit in the case (below).

• Memory: Corsair Vengeance LPX 8GB DDR-2400 - Seemed cheap (at least here in Canada) for an 8GB stick of DDR4.

• Case: Fractal Design Focus G Mini MicroATX Mini Tower Case I was hoping for something clean, simple with ports that are easily accessible. My parents still use the occasional DVD, so it'll need a slot for an optical drive.

• Power supply - Any ideas for this? I made the mistake of not getting a modular power supply for my PC (Corsair TX750) and now have a very messy tower, so I'll definitely want a modular one.

Here's where it gets interesting:

• Hard drive: I was hoping to transfer the 128GB Samsung SSD I currently have in my computer over to my parent's new computer. It's my primary HD and has windows 7 installed on it. Would there be any issues with the license if I move it over to a new PC? With respect to my parents old, dead, computer. It had a Windows 7 OEM license. Could I buy a new snazzy 500GB SSD for myself and use the Windows 7 key from the old, dead computer?

• Video card: I have a GeForce GTX 770 in my computer. I play about 2 hours of games a month (which the GeForce is more than capable running), but was thinking that if I need to buy a video card for my parents, would it be worthwhile to swap this into theirs and get one for myself? My computer has an i5-4670 processor 16GB RAM for what it's worth. I recognize this will be overkill for what they need, but I'm not sure if spending $50-$100 on a cheap video card for their new computer makes more sense. My other concern here is that the GeForce GTX 770 looks sizably big - any ideas if it would be compatible with a Micro ATX case/motherboard?

• Optical drive: I'll move the one from my PC to theirs as I haven't used it in ages.

I've already got all peripherals I think I'll need (monitor, mouse, keyboard).

Thanks in advance for all your help.