AVRs benefit from RISC instruction set and Harvard architecture and it is generally reported as the fastest and more efficient 8 bit microcontrollers.
I don't aim to teach the whole thing, I just see you like someone like me: you know C pretty darn well, you can read a datasheet and grasp a processor easily, you don't use and don't want to use pirate software.
Firstly get these software:
- Some AVR developers gathered all open source free tools to develop programs for AVR using C, that's WinAVR.
- Get the AVRStudio from ATMEL, it is free and you can interconect it with the compiler that comes with WinAVR.
Coming next :Part 2 or "Hey Man, where do I get information on the AVRs without wasting time searching on google or need to ask it in forums full of people that is easily irritated?" which I will answer pointing the good and free docs on the web that I took some time to find.