I have a Q6600 with 4Gb of Corsair Dominator PC-8500 ram and I'm running stable at 3.0Ghz at the moment using the 0608 bios.
My settings are everything set to auto apart from the following:
QDR = 1333
DDR = 667
vCore = 1.31xx (Can't remember off the top of my head)
Memory timings - 4,4,4,12, 1T
I played with it for ages to go higher than 3.0Ghz with 5,5,5,15,2T timings but it just wouldn't be stable for long enough. I'm bedding it in at 3.0Ghz now with these settings and then I'll try another overclock with the memory timings set tighter (maybe loosen to 2T).
I have tried using bios' 0701, 0803 & 0901 and all were rubbish compared to 0608 for me.
For those of you that are running a higher bios there is a way of downgrading as the ASUS update tool will fail on you if you try. Basically download a bootable CD from Bootdisk.com here
and extract the ISO from the zip. Open the ISO with something like MagicISO or UltraISO and copy the awdflash.exe and the bios#.bin file into the image and burn the CD. Reboot the computer and boot off the CD and it will drop you to a dos prompt that tells you what number your CD drive is using (in my case it was R:\\). Type r: to go to the CD drive and then type awdflash bios#.bin /f to start start the bios install. Click N to save the previous bios and Y to start the flash.
I've done this a number of times to go up and down from all of the bios versions without a problem.
XP 3DMark06 scores are around 16200 and Vista 64 are around 15300. Playing Unreal Tournament 3 and Gears of War totally stable at 1650x1050 and maxed out detail. The only game that still gives me grief is Crysis as I can only run at 1280x720 with DX10 Very High settings and average 25->30 fps.