If anyone is inspired to make a similar machine for their dolls, it'd be fairly simple to use a cheap keychain-style digital picture frame as a monitor, loaded with images for the screen.
Here's an example, though I can't vouch for this specific item or the company selling it. Maybe with a little more digging, you could find one with a smaller bezel that would look more like a monitor. Everything else (mouse, keyboard, CPU) could just be sculptural in nature, although adding a power LED in the tower could be a nice touch.