I want the url to be opened in Firefox by Powershell script
To make things a bit difficult, Firefox is not the default browser and it is a portable Firefox version.
Edit:
There seems to be some problem with my portable firefox installation. Even when making it the default browser, it doesn't work properly when invoked by start url.
I rechecked it with a fresh install of portable Firefox 4.0 from here and ittlefoot's solution works fine.
Using the website as the first argument should work.
X:\path-to-firefox\firefox.exe "http://website-to-launch.com/yadda"