Upon removing the x86_64 kernels, rpm removed everything from /etc/grub.conf. The only way I knew to get it back in was to remove the current stable x64 kernel packages and reinstall them by downloading from the web site and installing by rpm instead of yum.
[root@Char ~]# uname -a
Linux Char.ICS.local 2.6.18-53.1.19.el5.028stab053.14 #1 SMP Thu May 8 16:29:13 MSD 2008 x86_64 x86_64 x86_64 GNU/Linux
Memory for crash kernel (0x0 to 0x0) notwithin permissible range
PCI: BIOS Bug: MCFG area at e0000000 is not E820-reserved
PCI: Not using MMCONFIG.
ACPI: Getting cpuindex for acpiid 0x1
ACPI: Getting cpuindex for acpiid 0x2
ÿpowernow-k8: MP systems not supported by PSB BIOS structure
powernow-k8: MP systems not supported by PSB BIOS structure
ip_tables: (C) 2000-2006 Netfilter Core Team
Netfilter messages via NETLINK v0.30.
ip_conntrack version 2.4 (8192 buckets, 65536 max) - 312 bytes per conntrack
So the system boots into the proper kernel now. That's the output of the remote console. Is there anything there I should be concerned with? APIC is disabled in the BIOS, otherwise I had to specify noapic in the kernel options.