Current kit not HD capable?
The current Philips kit can output a 720p or 1080i signal over HDMI - indeed that's how I have it set up at home and the user interface is rendered in HD along with an upscaled freeview picture.
I've no idea whether it will support over-the-air HD (if that ever happens), but given that BT often pushes firmware updates to the box (as it's always connected to the internet through the homehub) it doesn't seem impossible.