Does anybody have *accurate*, *verifiable* information about the rules/law(s) surrounding laser shows / lasers being pointed in the sky in the UK? I am aware that laser shows require you to submit a document to the CAA per their website...
Rule of thumb for a good projector is $1000 per watt. You want scanners that are capable of 30kpps at 8 degrees at least. I doubt the projector you linked is up to the task, it doesn't even look like it supports ILDA input (which means you can't use it with quickshow), and the scanners will be...
I would just buy a standalone switch mode power supply. It is a lot easier, bearing in mind you have to short some pins on PC PSUs to get them to turn on. However, it may be a viable option since you get 5V and 12V rails on a computer PSU.
Be sure to disconnect the power supply from the diode before flicking the off switch. Lower the current to 0, unplug, then turn off. Or you will end up with spikes from some power supplies.