<<The older southbridge that was paired with it had problems as well.>>
Uh... KT266 and KT266A both used the same VT8233 southbridge. So, you're incorrect. The only problem with the KT266 is that it didn't perform up to expectations, the performance level was behind AMD760 initially, but improved substantially as mobo makers redesigned their board and BIOS, by the time KT266A was announed, the original KT266 has improved to 760's level and even outperforming it in many cases. All in all, the KT266 is not a bad chipset by any means, it's just as stable as KT266A, and it had little incompatibilities, people just hate it 'cause it didn't perform as well.