All Abit KT7 series motherboards have already been removed from AMD's recommended list. This is a total load of BS, frankly I think there are boards that are on that list that have worse problems than the "problem" that AMD stated with the KT7's.
In reference to the AGP instability comment, it just has to do with the simple fact that PCI video cards draw less power, have less driver issues, and will run easier in an overclocked PC system. BUT..... many people (in fact, most who overclock Durons and Tbirds) have AGP video cards and successfully run them. It's just a basic tenet of AGP vs. PCI. So what's the benefit of AGP you ask? Simple. Speed and Bandwidth. PCI video cards run much slower and have less bandwidth to the memory controller and CPU. So basically, if you have, say, a Geforce 2 MX PCI and a Geforce 2 MX AGP (of the same brand and amount of memory)in the same system, the AGP will beat the PCI hands down, any day. I know several people who, to reach additional heights of FSB overclocking, have chosen to run PCI video cards. It's just one less thing to go wrong, but you pay a huge price as far as performance goes.
SickBoy