BigPicture, this is good news for the ATI users here.
For people using NVidia cards, I believe that it is possible to get custom resolutions directly from the NVidia drivers (without the need for Powerstrip), provided one uses Windows XP
I've just discovered a workaround for Vista which requires connecting the projector via the NVidia component dongle (I'm using a component to HD15 adapter so that I don't even have to change the cabling to the projector - http://www.amazon.co.uk/Hama-Cable-A.../dp/B0002W6942
With this setup (which is enabled through the NVidia Control Panel - Display - Set up multiple display - HDTV), one gains access to a few new custom resolutions such as 1768x992i, 1360 x 768p, 1176 x 664p and to a few more refresh frequencies (25i, 29.x i) on top of the more conventional 1080iat 30Hz interlaced and 720p.
Via the resize HDTV desktop option in the NVidia control panel (and the projector's HPOS, VPOS and HSIZE settings), it is possible to have the desktop fill perfectly the projected image.
I haven't compared the picture this produces with what I used to have with my ATI 9600 (or done a full oscilloscope calibration), but it looks quite good.