funkyguy4000:
I have been thinking about getting an Arduino Due lately. Mainly because of the 32-bit (figured its better) and the faster clock.
The answer should depend on what you plan to do with it, which of course you aren't saying (don't feel bad, nobody ever does...)
funkyguy4000:
What are the key differences between an ARM3 Processor and a Microcontroller?
The Due has more RAM and more processing power, obviously. You might need that if you're making robots that need artificial vision or other projects that do a lot of math or manipulate large amounts of data. You also get more built-in peripherals, I/O pins, etc. Don't even think of connecting a 5V peripheral to one of those pins though or you'll be buying a new Due.
The AVR Arduinos make much more sense for controlling LEDs and general projects of the sort "read a sensor and use the information to control something else". They can take a LOT more electrical abuse than the ARM (and you can replace the chip for $3 if you ever do manage to blow it), you can make standalone versions of your gadgets for the price of a chip plus a piece of perf-board, you can get tiny Arduinos for small spaces, etc., etc. There's also way more web community for AVRs than ARMs.