Depends on the type of noise, and which inputs you see it on. Can you describe the ruck^h^h^h^h noise, sir?

You could be seeing normal picture grain on the DVDs, which you didn't notice before you got the bigger/better television. You could be seeing video data compression artifacts. You could be seeing ordinary antenna reception static. It could be signal degradation from poor cables, or from a substandard video switcher circuit.

It could also be a plain old ground loop... Those happen with video equipment, too (and a lot more frequently than you might guess).

Keep in mind that the "noise reduction filter" you mention is not meant to solve problems like ground loops, it's only meant to smooth out a noisy picture in much the same way that you'd blur an image in photoshop.