Checking in with a newly built system and my results so far.
The setup:
Asrock P43Twins1600 motherboard
Intel Pentium E2180 - 10x200 stock
Arctic Cooling Freezer 7 Pro heatsink & fan
4GB (2x2) A-Data DDR2 800
Antec Three Hundred case
PNY 8800GT 512MB
Seagate 7200.11 320GB HD
WD Green Power 750GB HD
NEC DVD-RW
Antec Earthwatts 80+ 500w PSU
This is the third E2180 system I've built this week, and my personal computer (the other two were for friends). The first was with a cheap XFX mATX board that was $20 after rebate in a bundle with the E2180 - that system is using the onboard Geforce 7150 graphics. The next system was on a Gigabyte GA-G31M-S2L mATX board, using the same PNY 8800GT I'm using in mine. Both of those are using stock heatsink (I am not).
(I was in a time crunch on playing with these two systems, as their respective owners were there for the build and Windows install/tweaking, and were leaving with the computers)
Build 1 - Ironically....the crap XFX motherboard is the only one of the 3 that would do 300x10 on stock voltage stably. That system has the cheapest motherboard w/ a very basic and not particularly intuitive BIOS, and the crappiest power supply (a 400w Rosewill that came in a $20 case), but is rock solid at 300x10 with the stock heatsink, and hits a max of 56C under load. I was not trying to push the limits on that system, as the user is not particularly savvy at tweaking - just wanted a good budget system.
Build 2 - LOVE the BIOS on the Gigabyte board - seriously pretty amazing. Would not boot at 300x10 at stock voltage. Had to raise the voltage a bit to get it to boot into Windows @ 300x10, but the Gigabyte board's voltage options were pretty limited IIRC and the "auto" feature upped the voltage by too much - temps climbed precipitously in Prime95 at 3ghz. I backed it down to 300x9 (2.7ghz) at stock voltage - runs a little warmer than the first system (59C load) due to case differences, but still a great running machine for the $$.
Build 3 (mine, w/ the Asrock board) - Extremely full featured BIOS, but simple enough to find the settings that matter for a basic user and leave most things @ auto. Amazing board for paltry sum of $69.99 I paid at Newegg. The Freezer 7 Pro + Antec Three Hundred case (140mm and 120mm exhaust fans directly next to the heatsink) keep things very cool - about 25C idle 50C load while overclocked at 1.4375 volts, with the heatsink fan @ 3 of 10 (800-900 RPM) and both exhaust fans on low. Nearly silent to my ears. I played around with multipliers 8-10, FSB's from 200-425. The processor I have does not seem to be stable above 3.2ghz, regardless of the voltage I give it (within reason, I haven't gone above 1.5V). I've tried 8x400+, 9x380+, 10x330+...all of them will boot into Windows at 3.4ghz+, but are not prime95 stable - and 400x9 = 3.6ghz would post (1.475V), but not boot (even when increased to 1.5V). It seems the sweet spot is 400x8 for me, keeping my RAM 1:1 @ DDR2 800 speeds. All of my voltages are on "Auto" except for CPU, which I have to keep at 1.4375 to maintain stability during stress testing.
I have no real experience with more expensive boards, but I can truly say that this board is a hell of a buy. $70 processor + $70 motherboard - definitely can't complain. SuperPi 1M is 18.891s @ 400x8.