I notice a substantial difference between DVD and blu-ray (even when the DVD's are upscaled to 1080), so buying them is worth it for me, as long as I'm not re-buying something that I already have with DVD.
If you don't notice a difference though, there wouldn't be much point to buying them since you can always get DVD's at a much better price.
@segalife: Size of display does not matter. It depends on your viewing distance. I could tell the difference on a 24" monitor if I was sitting at its normal viewing distance.









