I use the KG7-Raid in my 2 comps. and can truthfully say I have nothing negative to say about them... (ok, the $$ seemed a little high)
They are rock solid and run my stuff great.
Now, with that said, AMD is not interested in being a player in the chipset market and the 761 was just a tool to get DDR to market faster.
I think you are going to see better long-term support for the KT266A. It is also faster (although I believe you will need a benchmarking
tool to ever "see" that difference)
If I had to buy a MoBo today, it would probably be the KR7A-133 Raid unless the $$ was significantly higher than the KG7-Raid