480i,480p,780,1080?

Hi,

I am thinking about upgrading my video system. Right now it is a vcr, an old onkyo dolby pro-logic receiver, a 25" tv and some speakers. My reading about all the new stuff has gotten me confused. So..I guess DVD send out a 480i or 480p, but there are better sources out there. What is the hierarchy of video sources? Also, what features should a tv have to utilize these sources.

Thanks for the wisdom,

Rich