If you are serious about overclocking, build your own - the mobo's used by the big builders (Dell, Gateway, Micron, Compaq et. al.) are not designed or intended to be overclocked. They also tend to use the 4/3 slot setup rather than the 5/2 (PCI/ISA). Also the cases and fans are spec'd for stock use and quiet operation, not up to the demands of a serious overclocker.
Abit - Asus - Soyo all these MB will overclock fine. The Celery 400 usually over clocks easier than the 466. Get a decent fan and good RAM is also a good idea. If you plan to move into the 124MHZ + area PC133 RAM is a good investment. The Gateway E-machines are not good for OC. I think ALL their puters except the PIII450's and up are E-machines. You can buy a lot better machine for less money than the ones you mentioned. If I had to pick a major brand I would lean to Dell unless Micron was a choice.
For overclocking, building your own system is by far the best option. However, if this will be your first PC then let me assure you that it is worth paying that little bit extra for a professionally assembled machine, three year warranty and technical support.
Overclocking will void your warranty but it is often difficult for manufacturers to prove that you have been doing it. Therefore, most of the larger OEM's use special versions of mainstream motherboards which cannot easily be overclocked.
All that aside, I have an older (PII-233) Gateway system on which I do overclock my CPU, monitor and video card.
I'm stuck with a Gateway P2-300 for my gaming/Inet comp till my replacement is finished. Anyone have luck OCing these? I used softFSB and got 360.1 Mhz@85 fsb stable, but my 7200 rpm hdd got *really* hot (burned out in two weeks). Basically, anyone know a good way to futz these nasty little Gateway machines to 100Mhz fsb? I've changed the ratios for AGP and PCI, but it gets too hot at 85Mhz with standard ratios and too slow with new ratios.
And the beat goes on...
[This message has been edited by Forge (edited 07-29-99).]