obviously you have a 32 bit OS, so the 64 bit installer is useless for you
besides, after downloading the file run "chmod +x" on it to make it executable
and please, do yourself a favor and never run anything as su / sudo if you don't know what it does. Though the PlaneShift installer is not going to damage your system, but other software might and if you run it with sudo it will have root access can just do whatever it wants
so the proper way to do it:
Download PlaneShift-v0.4.03-x86.bin
chmod +x PlaneShift-v0.4.03-x86.bin
./PlaneShift-v0.4.03-x86.bin