Yeah I have the freeware version of IDA pro from back when it was still owned by Data Rescue, it's the best disassembler money can buy, the full version will even disassemble code that runs on mobile phones.
Sadly the free trial is stripped down and will only debug win32 apps. I remember reading that not even the full version will debug most of the code that it can disassemble (ARM, MIPS, etc)