Encode Decode, make smaller

Dont know if its called encode or decode or whatever, but i got a raw footage with my digital camera on my computer, that i want to make smaller. Its like 1gig+.
It is 20 minutes, i would love to get it down to 100-300 Megabyte and still have its good quality..

Are there any good programs out there that can do this?
I heard Divx is alright, but what do you guyes think?

 

http://www.afterdawn.com/guides/

http://www.doom9.org/

http://www.videohelp.com/

These links have instructions, information and programs that will help you.