Oh, I didn't even see that X segfaulted.
Well... there are a bunch of probable causes for that. Does stepping down your AGP speed help? Are you sure the AGP drive strength is OK in your BIOS? (it very likely is, but you never know...) Are you using agpgart or nvagp for the AGP driver? (you can tell by the Option "NvAgp" line in your XF86Config -- 1 is nvagp, 2 is agpgart, 3 is try agpgart and fallback if it doesn't support the chipset, and 0 is disable AGP completely -- and if there's no line there, the default is 3.)
Which version of X is this? X -version to find out. I wouldn't think anyone at RH would be dumb enough to put something like 4.2.99 in, but you never know...