Hi i want to buy a digital camera and I'm confused between canon, Nikon,Sony or lumix?

I want the camera for more a professional use with a big zoom and high rez and i can changed the lenses like D50 or H1 or R1 or FZ 20,30 but i want the price between 350-450 $

It depends on what features you want to come with the digital camera. Canons are normally for more professional pics, and Nikons are just a bit lower on the professional scale. Sonys are oriented around everyday comsumers, and Lumixs are just a bit lower. It really depends on what you want to use the camera for.

Nothing like Canon for quality!

If you know the technics of a (D)SLR: Canon or Nikon, with the possibility to change the lens.

If you like "all in one": Canon or Panasonic.

Well, I'd go with the Nikon
(that's the camera I own)

But, because of your price range, I don't think it's as much of an option unless you get it used or refurbished.
Because usually for body only (new), it's around $550...Unless you get it new from Ebay or something

i would go with the Nikon, but for the price range you will not be able to find a digital with interchangeable lenses, unless you buy a used one.