Quick notes:

• RHEL5 always uses a Linux Timer Rate timer rate of 1000 Hz. This can be decreased in RHEL5.1 for greater efficiency of RHEL SMP guests.
• RedHat has not enabled VMI in their kernels, so out-of-the-box paravirtualization is not possible. But custom kernels can easily be built to take advantage of this feature. See VMware KB article #1003644.