I'm afraid i don't know too much about codec's and which ones are for high quality and and which are for streaming. I have a project shot in 720p and i did an export movie without looking (stupidly) and it exported in 480p and looks aweful. so now i have been looking around and i don't know the best way to export should i use the adobe media encoder or the export to movie? Also what is a really good high quality codec that would work well with 720p.

Generally speaking, h.264 is the "Swiss army knife" of delivery codecs. It's used for Blu-Ray disks and is probably the most common codec for non-Flash Web video. It offers the following advantages:
-Superior image quality
-Excellent quality:file size ratio
-Very portable across different delivery platforms

I'm sure there are others but those are the ones that leap immediately to mind.

Peter, as you yourself say, there are different codecs for different purposes. What's your purpose in this case?