DVDO iScan HD is ideal because of the excellent test patterns, and I have similar ones to set up my HTPC.
Set the iScan HD to default timing setting for 1366x768, then adjust the horizontal/vertical size/position on the plasma display; it's really easy on Panasonic plasmas (unlike the Pioneer ones for example).
Getting 1:1 match on analogue VGA is really easy, three simple steps:
1. Use horizontal size control on |||| test pattern until the "rainbows" go away, they are different colour interference patterns as you pass the centre position (either getting horizontally bigger or smaller); in centre setting there is no interference pattern.
2. Use vertical size control on === test pattern until the "rainbows" go away and you've got solid black'n'white lines.
3. Use horizontal an vertical position on iScanHD's first test pattern until image has single pixel white line round the edge.
This takes seconds: one-to-one pixel match is demonstrable on every test pattern.
The screen has a number of "memories" for different resolutions/refresh rates set to it, once you've done this once it stays.
Super-Advanced Users do this within the Service Menu so that once the horizontal/vertical size/position is set to 1:1 match it becomes the "normalize" setting in the "Picture Position" menu.
As I said above this is with analogue, the DVI does not let you do this. DVI really is poor on Panny plasmas, but their analogue is stunning and the PQ once one-to-one set is almost indistinguishable from DVI -- they must have good ADCs or over-sample or both
Once you have 1:1 match on screen with test patterns you may still see black borders with some video sources: typically thin at top and bottom and fatter at the sides, the edges may even be blurred or wavey. This is where the source isn't using the entire bandwidth available to it, however, this is solved simply with "Overscan" setting that can be increased until the image files the entire 1:1 matched display.Pioneer 50" MEX plasma
I've also set up analogue and DVI with one of these plasma screens. Again timings were straight out the box defaults for the native 1280x768 pixel resolution, but the challenge here is the internal frame buffer of the screen is fixed to 70Hz.
Via analogue this was a simple fix with iScan HD because we set PAL and NTSC material to Frame Rate Adjust to 70Hz; DVI was more of a problem because it would only accept 60Hz, and then it's internal frame buffer converted it to 70Hz.
Still, both analogue and DVI were 1:1 matched at 1280x768.
Again with these Pio screens I'd recommend analogue connection because of the ability to display the native resolution at the plasma's fixed internal refresh rate.