Gigabyte GA-8TRS300M. Features onboard ATI 9100, lan, usb2, agp, pci's etc etc. Currently runs as my brothers computer, using a Leadtek 6800GT. Overclocks his Pentium 4 Prescott 2.8 all the way up to 3.1 (as that is the max FSB selectable... 230Mhz i think).
There are basic memory timing settings and some other ajustments. I seem to recall (and this is off the top of my head, so excuse mistakes), if i set the board to it's own O/C 'Fast' memory timings, it improved (tightened) the timings on the memory, but wouldn't reach past 225FSB. I benchmarked at both automem timings at 235, and tight timings at 225, and the faster FSB setting with auto timings was faster across all benchmarks. Remember, on all Gigabyte boards you have to hit CTRL + F1 in the bios to access the more detailed engineering settings.
He changed to the gigabyte board because his orginal Gigabyte FX5900XT didn't work in the following board...
The Aopen MX4SGI-L. It too allows FSB ajustment up to around 235 i recall, which is the same as on the Gigabytes. I think it must have been some sort of Intel recommended 'maximum' allowance for boards that size (lack of 4 phase power on micro's perhaps). It features GIGABIT lan, but no on-board video as I recall.
So there you have it. Prescott support in a MicroATXs with not unreasonable o/c settings. I would recommend the Gigabyte in general, but i love the Aopen's gigabit lan and the fact it had to be imported from Japan with my Scythe coolers brings a happy memory to mind
It should be noted that both boards have caused their fare share of 'issues' with certain hardware. The Gigabyte board almost destroyed an XFX 5900XT (due to it's wild agp voltage spikes - doesn't seem to affect Gigabyte's own-brand 5900XT), but the Aopen loves the XFX. But Aopen hates more 'specialised' types of RAM.
If you are going with basic hardware, either board will do you fine.