Christian,
What you're seeing is a more generic install that's included with mainstream Linux distros (like Redhat or Mandrake). Those distros can be installed to a wide variety of platforms and based on the discovered hardware, will install what's necessary to work. Many will have different distros for different platforms too like MIPS or Alpha or PowerPC. I think in your case, the processor is just too old for SME to run, which is based on a Redhat distribution but geared toward a specific minimum processor configuration for Intel processors (SME may support different processors/architectures but I have no experience with running SME on them).
I'm sure you can find a distribution of Linux that will run on your system but it looks like SME may not be your best choice, unless you want to upgrade the hardware or go with an older version of SME server.
Dave