I have never used a Soyo mobo but from what i have read and from what friends have said that have used them for themselves as well as clients, quality is very high and they seem to make a very solid product. I think more than anything you need to look at the chipsets themselves regardless of mobo maker. That is the most important aspect, and if you choose to go with a P4 then by all means go with an Intel chipset.
I recently put together a P4 system and have had problems with the mobo. I have a Shuttle AS45GT, based on the SIS 648 chipset. I read up on it and every site i checked gave it outstanding reviews. My experience from a mobo that worked for about 3 weeks then died and more recently the problems i have had with the replacement board have left me with less than impressed. I got it to work again, but it is now running at 200 mhz for the memory bus, even though i'm using ddr 266 and it should run at 266. I this point i am so frustrated by it i am saying f*ck it!
Next box i build will be a duel Hammer, duel Xeon, or duel Yahmill (if it comes out, LOL). But that is a few months down the road. Oh well...
