you want to install the nvidia drivers, which are not included with redhat.. they will make the DVI stuff work much better.. You should also grab redhat 9, it's much more functional than 7.3 when it comes to a more modern machine with DVI and such.

URL for your entertainment.
http://www.nvidia.com/object/linux_display_ia32_1.0-4363.html
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80gig red mk2 -- 080000125
(No, I don't actually hate Alan Cox)