I don't think 3D will come across too well on smaller screens. I think even 40" screens are too small for 3D. I feel that the screen should fill the majority of your vision to create a better effect, otherwise you're seeing a 3D screen against a 2D background.
Thanks guys for replys the 26 inch screen that I use now is in the conservatory which is used for standard def sky and gaming on ps3 with a viewing distance of about 1.8 to 2 meters so I think that a 40 inch screen would be good for the gaming but not sky standard def,any thoughts.