Yes tech support is right.
They do not support xorg 6.x, you need 7.x for parallel TOOLS to work. However, RH4 will work correctly. You just won't have the automatic resoloution adaptation of X, or the seemless movement of the mouse between the VM and the OS X. ( meaning you'll have to press CTRL-ALT to bring back mouse and keyboard control back to OS X from a RH4 session).
For your info, it works very well with Ubuntu, Kubuntu, OpenSuSE.
If you have Xorg 7.x available for RH4, you could upgrade to that version of X and you will be in business.
Last edited: Jul 13, 2007