Any idea what the first mac laptop or tower/card to support monitor rotation is?

[pRICE cUBE]

I want to hook up a monitor to put in a hallway that displays pictures, videos, announcements on a vertical screen. My mind and my searches are not bearing fruit as to what Mac laptop supports a vertical external monitor orientation. Maybe a tower would be cheaper or g4 mac mini? What OS combo and what cards supported this? I am looking for the lowest possible price as this is for a non profit group. I am also open to...doing this one a pc....uuuuugh.

Thanks in advance.