Xibo supports PowerPoint provided the machine also runs a full copy of it - although we encourage people to export their powerpoint as a video as it results in a far better experience overall.
You can grab a 14 day demo CMS or download it yourself and pop it on a web server somewhere within your organisation - then install the 1.7.5 player software from here - its pretty simple to set up so I am sure you could replicate what you currently have inside of an hour.
Not really i’m afraid - it is non-trivial to demonstrate the software in any sort of understandable fashion - its probably best to look at the getting started guide and then the FAQ to decide if its worth trying out.