RHEL vs MS Window - which is better OS for Ansoft HFSS?

Hi every body,
I'm using Ansoft HFSS v10 for my simulation. We are well known this software suport both Microsoft Window and Red Hat Enterprise Linux v3. However, I run it on Microsoft Window XP environment, it's slow because of hardware's limitation.
I'm planing to use HFSS on Red Hat Enterprise Linux v3 environment but I wonder which OS is better than the other?
Anyone give some experience?

Thank in advance!