You'll need a 64-bit machine/CPU to be able to install a purely 64-bit version of Linux. AMD64, Opteron, Itanium, UltraSparc, PowerPC, something like that. A regular AMD or Intel cpu like Pentium4 or Athlon are 32-bit CPUs. What hardware do you have?
Oh and I'm pretty sure there are versions of Oracle 9i for Intel i386 32-bit available.