One of the less noticed changes to Windows Vista is that it no longer supports displaying in ‘full screen text mode’. This means that if you open a command prompt – you cannot put it into full screen mode.
However – you can put a Virtual PC virtual machine that is displaying text into full screen mode. The reason for this is that Virtual PC emulates its own video card, takes the display information from that emulated video card, and then uses DirectX to draw it as one big bitmap to the physical computers screen. So while you may be looking at what looks like text on the screen – Windows Vista just thinks it is a bitmap.