To use a Raspberry Pi as a thin client:

You will need a computer and a Raspberry Pi both connected to your network (preferably with cables rather than WiFi)
Once you have one VM working you can clone it and (if your computer is fairly powerful) have a number of Raspberry Pi's connected to the VMs. I'm not sure on the legality of cloning Windows VMs.

How well does it work? Well enough for editing documents but not enough for watching video.

To look into: