OMG - you have a LS120 drive.
I still have a box a discs for that drive that I brought something like 25 years ago and never got around to using, hard drives started to become standard around the same time!
colour me impressed. that rig has indeed got valves and a crank handle.
and there-in probably lies your greatest hurdle.
ideally you should install a OS that matches the generation of hardware it will be running in.
so ideally Windows XP would be the best fit - but it is long past its end of life cycle.
I fear Win10 either simply won't install or if it does, getting video, sound, and network drivers (for starters) will be an Herculean task.
since it had Vista on it, there should be a glimmer of hope.
to get you started, change the boot order to USB-HDD first so it reads the USB with Win10 on it.
and leaving the 1GB memory stick in for now will be fine - just bloody slow.
and that leads into your next issue - Win10 likes at least 4GB of memory, it'll work with lower specs, but at slower speeds.
I suspect your processor will also be under-powered.
AND... it wants around 20GB of hard drive space.
I reckon the more you travel this path, the more you are going to come up against hurdles and eventually you'll either come up to one you can't get around or the combined effect of all the limitations of the rig will have an overall negative impact on its usefulness.
and then there is the sheer age, and the likelihood of hardware failing.
sorry to be Mr Negative.