I'm not sure what the procedure is under Redhat or Mandrake (i use SuSE), but you need to edit your default runlevel to '3' instead of '5'.
If you use grub as a bootloader just hit the "up" arrow and enter the number '3' in the boot parameters line (bottom of the screen). Otherwise, your distro shold tell you how to change the deafult runlevel in the user manual. (I hope!!)
Hope this helps.