any suggestion about a particular motherboard?

[babyboss]

as above.

[mdwatts]

I've been very pleased with my Asus A7M266-D (dual AMD's). Running 9 months now and not one single problem.

[Timothy L. Miller]

I've got an ECS 7KS5A that works great. It's a bit older technology (SIS 735 chipset), but it cost me like $55, has onboard networking and sound that work just fine with Mandrake, Yoper, Libranet. I haven't tried any other distros, but I'm sure it will work just fine with them also.
Another board I like is the MSI KT3 Ultra 2. Has onboard sound also, but I don't know if it works, since I use a Soundblaster Live! in it. It's based on the VIA KT333 chipset. Very fast and stable. I've ran more distros on this computer than I can count, with no problems.