Please note the following links are external to this website.
Dontronics - World's largest range of Microchip (PIC) and Atmel (AVR) Hardware and Software.
Microchip - Microchip Homepage, download their free assembler included in the MPLAB Integrated Development Environment (IDE).
Freescale - Freescale Homepage, download an evaluation version of their tools, CodeWarrior IDE.