To compile 64 bit?

Hello SuSE people. Question: Am running an AMD 64 processor. There are still not all programs that are 64 bit. I know that the system will handle 32 bit stuff but I was wondering if an src file can be compiled to 64 bit. Ex: Tonight I went to download smart at Guru's site. There were no 64 bit versions, only i686 and src's. I hesitated to download either because I didn't know if either of them would work without problems. Bob S..