I have a 42" Plasma 1080p that I have hooked up HDMI to an upconverting 1080p DVD player. If I was to buy a Blu Ray player would it give me a better picture than the regular DVD player?

Yes.

Do you know why? I thought that if my DVD player was upconverting it would give me the best possible picture for my TV

Upconverting is creating picture information that doesn't exist in the source. The HD disk formats display detail that is present in the source.

The Blu-ray player will give you the better picture. A movie on a Blu-ray disc is mastered at 1080p. A SD DVD is mastered at 480p. You cannot get something for nothing, that is you cannot upconvert a low resolution source and expect that the quality will be as good as a high resolution source like Blu-ray discs.

Well, for starts DVD is a low resolution format. Blu-ray will be full 1080P and will also have much more vivid colors and better detail. To me all DVD's just looked washed out in comparison to blu-ray. Much like the way DVD made VHS look.

No matter how much you "upconvert" you can't add detail that was never there to begin with.

Thanks for the quick responses!

To answer your question truthfully (I have a 42" 1080p and Blu-ray) yes and no. What I mean is that a poorly encoded Blu-ray may look no better (or actually worse) than a good transfer Super-bit standard dvd unpconverted. That's just the extreme though...for the most part Blu-ray is going to be much better than standard dvd upconverted or not. Just don't expect every Blu-ray you pop in to blow you away...they aren't all created equal.

I thought the OP was wanting to know if their DVD discs will be upconverted with a blow-ray player and have better picture quality. It seemed a no-brainer that a blow-ray (or hddvd) disc would look better than a dvd.

If you are asking whether your standard DVDs will look better, I'd say no from what I've seen. Of course Blu-ray discs will look better than upconverted DVDs as they has much more information to display, but a good upconverting DVD player will make your regular DVDs look great. I see no benefit of getting a blu-ray player unless you plan on buying blu-ray discs.