Can I use a 17" LCD with the standard lens? Sort of. The standard projection triplet is capable of handling a 17" LCD. The fresnels are the problem. The standard fresnel kit will not cover a 17" LCD. you can use a program such as powerstrip to reduce the used area on the 17" LCD to something that the fresnels can cover, or you can source larger fresnels elsewhere.

This also applies to 15.4" widescreen LCDs, since they also will not fit with the standard fresnels.