How to run a PowerShell script without displaying a window?

You can either run it like this (but this shows a window for a while):

PowerShell.exe -WindowStyle hidden { your script.. }

Or you use a helper file I created to avoid the window called PsRun.exe that does exactly that. You can download the source and exe file from Run scheduled tasks with WinForm GUI in PowerShell. I use it for scheduled tasks.

Edited: as Marco noted this -WindowStyle parameter is available only for V2 and above.