os there any way to dissasemble a program to asm, then try to figure out what c source was used to create the program?

what i am trying to do, is dissasembe a closed source program made for a 32 bit computer, and use the source code to build a 64 bit version of the program so i can make use of all the 64 bit power my computer has, and i'm dying to use... please help, it must be possible, it is important to me.

I've heard of programs that try to do this. None of the reviews were very poor. Because there are many ways to optomize c when compiling, it is very very difficult to undo these optomizations. One project I found after a very short google search was this http://www.backerstreet.com/rec/rec.htm. I'm sure there are others, but I haven't heard very good things about them

Sorry.