if it is simple i386 it means it is of 32 bit software, now many type of architecture is available in market now a days like i386,i586 i686, so in generally software provider say it as x86 architecture. now if x86_64 is there in the description then it is software for 64 bit architecture otherwise a 32bit software.
second the diff. between live CD and DVD
with live CD in your drive you can simulate the environment and taste the look and feel but it will not install to your system as a separate OS. With DVD you have to install the OS in your system as a separate OS.
I think this will clear the things if not please post here again.