I am studying now and what I am doing is the following.
Go
here and copy and paste the exam objectives for each of the tests (RHCT and RHCE) into a document.
Take each bullet point, and read the
sysadmin guide and the
reference guide and try to figure out every angle they could test you on that subject and document it under that bulletin point.
Once you have everything documented, go and get yourself a copy of
vmware server and an eval copy of
Red Hat. Get vmware server setup on a machine, then install Red Hat as a virutal machine. This is nice because you can create multiple virtual hard drives for the Red Hat install so it allows you to mess with software raid and lvm without having to spend money on multiple hard drives. Also, you don't have to have an extra machine to put Red Hat on.
Then take the study guide you created, and create a couple install/config scenarios. Pick a task from each bulleted point on the study guide, and install to those configurations. Once setup, make some changes, try some things, then blow away the virtual machine and start over on a new/different configuration.
This will probably be one of the best ways to prepare for this exam as it is performance based, not question based. Test Kings would be a waste of time and money. The best advantage of how I am studying is all the material (assuming you have a computer) is free.
Good luck on the exam!
edit...
I also found
this script which I haven't used yet, but it will cause some trouble on your system when run that will give you troubleshooting scenarios, which is a part of the exam.
How to start for RHCE 4.0
