The answer to the question How can I most easily break mission-critical systems using half-baked software?

ReactOS is for hobbists that don't mind if their toy OS crashes every 3 minutes or so.

Give it to 'em, man. Real engineers maintain their mission-critical systems by running their obsolete software on obsolete budget consumer PCs.

ReactOS really sounds promising for these specific areas and I hope it gets better and better with time, it's just a shame that it's development cycle is slow right now though I understand it's hard to reverse engineer Windows

Not to Windows 98; IIRC ReactOS strives for compatibility with the Windows NT tech tree.