Just wonder if its possible to use my Arduino programming environment to program other AVR MC's;
Well the Arduino IDE works with several of the AVR processors. Some are avalible just by selecting the proper board from the IDE selection window. Other chips require a modified IDE and several vendors offer free modified files to support other chips like the 644 that the IDE does not support unmodified. Perhaps it would be easier if you just listed the AVR chips you are interested in and we can see if there is any support for them. To adapt a unsupported processor takes quite a few modifications to the IDE files including the bootloader code, I/O pin mapping, etc and of course the AVR chip must be supported by the gcc compiler that the Arduino IDE uses.
Lefty