[museav]

Using multiple projectors to project one larger image is called edge blending and for it to work correctly the images have to overlap to some degree and quite lterally have the image blend across the two. Some projectors incorporate this capability, but it likely won't be included in cheap projectors. There are also external processors that will provide this functionality as well as it likely being accommodated in some software packages. I would be a little wary of the ability for 'cheap' projectors to provide the image geometry adjustments necessary to truly align the two images.

Otherwise, I agree with teh others that the best approach is probably to use a dual video card and live with whatever compromises and issues exist where the images come together.