I think SELinux is a red herring in this case; I'm running upstream RHEL Server 6.3 32-bit with SELinux in enforcing mode on an older Supermicro system (motherboard P4DP6, has a DVD-ROM CD-RW drive in it) with the following CPU:
The problem with the selinux rpms is that they need copious amounts of RAM during installation. From my experience, a minimum of 0.75 to 1GB.