ia-64 or intel64 for linux64bit

Hi I got 3 computers,

1. is a quadcore Xeon E5410 (/proc/cpuinfo lists 4 cpus)
   
2. is a dual quadcore  X5570 (/proc/cpuinfo lists 16 cpus)
   
3. is a dual quadcore  X5450 (/proc/cpuinfo lists 8 cpus)
   

And I want to try out how the intel compiler works for me,

but can anyone clarify which compiler to use (intel64 or ia-64)

I'm using an ubuntu 9.10 64bit

Thanks in advance