Hi, here are a few answers to some of the questions
1. Clock speed wise, Duron is no comparison to Athlon Thunderbird due to its smaller L2 cache. Duron is designed by AMD to compete with Intel Celeron and wins hands down, not with its own Thunderbird. However, Duron 950 runs lower temperature than Thunderbird 950, meaning you can get by with the AMD supplied HSF, and uses less power. I'm currently running this combo using 250W PS without any problem.
2. IMHO, ECS K7S5A is not designed for overclocking at all, so don't waste time doing it. Also, overclocking will void your AMD warranty, and you'll definitely need a very powerful HSF. It is basically a low cost alternative for people who want to upgrade to the socket A platform. You can still use your PC100/133 SDR SDRAM without much performance penalty. Later on, you can upgrade to DDR SDRAM and Athlon XP with the same board. If you are upgrading from socket 370 or super socket 7 platform, you'll be amazed by the performance jump. If you have experienced VIA KT266A motherboards, this combo is not for you.
3. Duron with Morgan core (1 Ghz and above) has incorporated SSE just like XP. If you do a lot of video encoding stuff, like burning your own video CDs, you'll definitely benefit from it. But then, you should probably get an Athlon XP instead of Duron.
4. You can get a much better deal by buying a combo, but make sure you know what you are getting into. Fry's combo deals are hard to beat, but their component's individual price is not attractive at all.
5. Overall, this is a great deal for a low cost upgrade, and I highly reommend it for people using their computers for general purpose. If history is any indication, Outpost.com will probably offer Duron 1 Ghz with the same motherboard for $89 in a month and a half if you are willing to wait. Hope these help, just my two cents.