Newbies to compiling the linux kernel would definitely be interested in a thorough answer to this.
NUMA is a "relatively" new (2003) architecture for multi-core processors that has quickly over shadowed SMP for many reasons. I won't go through them all, but a big one of them is scalability (SMP can only scale to 8 cores). As far as I know, as of the time I'm writing this, the only type of processor's available to the general public built with the NUMA architecture are the Intel Xeon 5500 processor series, the Intel Core i7 series (google 'Intel Nehalem'), and the AMD Opteron processor series.
The cool thing is Intel is getting close to releasing their next generation of Itanium (google 'Intel Tukwila') processors and more 'Nehalem' processors.
Also, NUMA processors require special chipsets to help maintain cache coherence (google 'ccNUMA'). So even if you got the chip and a mother board with a socket that will fit it, it doesn't necessarily mean you can enable NUMA.
Wikipedia has a good article on the NUMA. It doesn't have everything you may be interested to know about it, but with a little digging, you can find quite a bit of information.
I hope this is helpful and expands a little bit on why you and others are not able to enable NUMA,
Last edited by ambius; 05-25-2009 at 12:16 AM.