Rip,
http://www.pricewatch.com Search for your components there, it usually gets me the best prices. Also be aware that you may have to pay slightly higher on one of the itmes in order to keep it coming from one source to keep shipping prices down.
I just ordered components for my sister's college comp (PIII 667EB) from
http://www.computer-x-press.com I found the PIII 667EB (Coppermine 256k external cache, 133 Bus) to be the best bang for the buck at the moment, I got mine for $192 from computer-x-press by mentioning the pricewatch listed price. I ordered a tripple-fan and heatsink unit for the PIII along with it. ($15) I've had good luck with Abit motherboards. I ordered the Abit VA6 for my sis's comp for $65. It has onboard sound and a 133 bus, along with the usual AGP and PCI slots. I haven't received it yet, but reviews of this board indicate it to be a VERY stable board, but it lacks in speed slightly from the latest BX chipset. For a bit more you can get an Abit board with the BX chipset. The Abit BH6 in this machine is doing well, and it was simple to set up. A good set of PC133 RAM should do you well. Beware of the lower priced RAM, it may not be as high quality as others. I ordered it for my sis's comp 'cause she isn't into 3D games or anything that needs absolute peak performance.
If you're going for the PIII processor, get an EB. EB means it has both the 133 bus and the coppermine 256k external cache which is supposed to perform well. And make sure you get the right type of processor for your board. If your board is a Slot-1 board, make sure you get the SECC-2 chip. If it is a socket board, get the FGA/PGA chip. They sell adapters to convert the socket chips to slot-1, but you'd be better off just getting the right one for your board
From my searching, Athlon chips are generally cheaper, but I found that decent motherboards for these things cost significantly more than a good PIII board, plus I've only dealt with Pentiums, and like to stick with something which has proven itself to me.
128MB of PC-133 RAM should be plenty for Win98 in my opinion. A good stick of PC-133 16*64 DIMM RAM should run from $140-160. Again, if I were building a gaming computer, I'd go with a brand-name set of RAM over the cheaper generic stuff.
Also, if you get a new motherboard and plan on using your current case, be sure you get the right style of motherboard. If your motherboard is an ATX one (reccomended) make sure you have an ATX case to mount it, preferably with at least a 235 watt power supply. I like the Apex cases for their low price yet high quality, along with easlily removeable sides.
I've only built one computer, and the parts are on the way for my 2nd. I'm still learning this stuff, but if you have any other questions, I can try to answer them for you.
Hope that helped.
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Mark VanZwoll
33rd Strike Group