Compiler Upgrade : Need to verify exe results ?

Hi experts,

I'm planning to upgrade our fortran compiler from Intel Fortran Version 11.1.060 to the latest available. 

I will keep the same compilation flags. 

Is there a risk that the results of my software are different ? In other word, do I need to validate my software ? 

I've more than 100 small programs and this might take me a lot of time. 

I also have the same question if I move from 32bit to 64bits.

Thank you,

Vincent