Ok Gentlemen, I've got the official answer I've been waiting for. All of the input that this forum has brought forward has been right on target though some were a little hard to follow.
The AMD tech support guru I talked to today has confirmed that the MP CPU will drop right in and work just dandy as any 2600/266 Barton core should even if the BIOS doesn't officially support it. The tech also bet it would report itself as an MP, but it could fall back to the XP identity. There should be NO
issues with using this CPU at all. Also once the processor is in place I'll check it with the AMDCPUID.exe program. [AMD Processor Utilities
Together we reasoned that more people aren't pursuing this upgrade is because they don't know about it or it's seemingly not viable & finally the extra cost. For the ~$150 that I'll be spending on the CPU, some folks would rather double that & buy a new motherboard & CPU. But that doesn't consider the adoption cost of new faster memory either or the major hassle of reloading a hard drive. Meanwhile I'll also be saving my GAB/266 of memory too.
As I said before, this upgrade is going to allow me to wait a year or more until the 64 bit adoption costs drop. I'll write back with the results once I get it together.
I want to thank all of you for your input & support.