I have a couple Megatouch XLs running original Motherboards & I/O boards along with AT Power supplies,
serial ELO monitors, & the platinum "upgrade" drives from fleabay. (well, one is up and running anyway) The fleabay drives will work with any XL key. I'm actually running compact flash cards with IDE adapters.
Unless you're familiar enough with the software to be able to get by with less, you pretty much need everything.
There is no bootleg software or emulator out there on the internet that will allow you to play Megatouch games on your PC.
(except for the very old versions in MAME)
It shows it's age, but the Touchmaster series of games is playable in MAME.
Just calibrate your touchscreen like a light gun.