Economy PC's...

I just built a nice Athlon 1.4GHZ system with Soyo SY-K7V Dragon Plus mobo (KT266A chipset). That is my main system for my home/business network.

I have two older systems, (both, AMD K6 400mhz) which I am going to upgrade. They are all used for normal business applications, nothing graphic intensive.

The upgrades will include: Mainboard, CPU w/fan, Memory and Case. I will utilize my existing hard disks, video/audio cards, CD Roms etc. My original thought was to upgrade just one of them, and build it exactly as my main system, but decided I could upgrade both for about the same price by choosing the 'economy route'.

I know that the KT266a chipset is superior to the SiS735. From the research I have done though, the SiS735 chipset is not bad, and is in fact superior to the AMD 760 chipset. For whatever reason, the Mobo's with the SiS735 chipset are very very inexpensive.

http://www.tomshardware.com/mainboard/01q3/010924/index.html

Before this turns into a book, here is what i have in mind for my two 'Economy PC's':

Mainboards: Elitegroup (ECS) K7S5A $53 ea.
CPU's: AMD Duron 1ghz $49 ea.

And since the ECS board has two sockets for DDR DIMMS and two more for standard SDRAM, I believe I can use my old PC100 SDRAM, of which i have 256megs, enough for one computer.

A few questions:

-Any experience with this motherboard, or other suggestions?
-What watt power supply do I need?
-How do I know if i need PC133 or PC100 SDram?

Thanks,
Mason