Aspect ratio of 2560x720....
2560/720 = 3.56:1 aspect ratio. :nudgenudge
Movies are 2.35:1, so 2x 720p is too wide an aspect ratio for a media center setup. Blu-ray is 1920x800 actually.
If you want to be closer to 2.35:1 for a media PC, it would be better to go with 2 1024x768 projectors which = 2.67:1...a lot closer to that 2.35:1 aspect ratio and a bit more pixel resolution on the height than 720p projectors. Multiple 720p projectors are the least ideal for a media center pc.
For a media PC 2x 1024x768 projectors much better fit the Blu-ray content spec. 2048x768 is very close to 1920x800.
Here is an example of 2048x768 watching HDTV before I went circular projection. To give you a sense of scale, that is a 13 foot wide room. You go wider aspect ratio you lose projection height.