the Q6600 has a good price/value ratio so it seems to make not much sense to get a less powerful processor ... some headroom doesn't harm too and if you're looking for a silent system you shouldn't run a CPU at its limits ... maybe one would like to add some plugins later?
of course also 16 GB are nice to have, maybe only as an upgrade option ...
i had some bad luck with gigabyte boards earlier and it appears asus support has become kind of slow ... during the last year i'm tending more to intel boards ... but this is more a matter of taste than objective decision ...
christian
ps: currently building this system (you already assume it has to run more than a few VE instances) - too bad no 5400 32GB board exists currently except the macPro:
Skulltrail S771 E54000 EATX - S771/ EATX/ 4x banks/ max.: 16GB/ SD-RAM, DDR2/ 667 MHz, 800 MHz/ fully buffered/ HDD: SATA II, PATA/ no AGP/ 2x PCI/ no PCI-E x1/ no PCi-E x4/x8/ 4x PCI-E x16/ no PCI-X/ GBit/LAN/ RAID, Onboard Sound
2 x QX9775 or X5482
2 x Kingston 8GB 800MHz DDR2 ECC Fully Buff - (2x4GB Kit) Standard 512M X 72 ECC 800MHz 240-pin Fully Buffered DIMM (SDRAM-DDR2, 1.8V, CL5, FBGA, Gold
3 x Seagate Barracuda ES.2 1TB 32MB - : S-ATA 2/ 1000 GB/ 7200 rpm/ Cache: 32 MB/ 3,5 "/Raid
1 Seasonic Ultra Noise 700Watt ATX PSU
Noctua socket 771 NH-U12DX cooler max. 19,8db
Lian LI PC-A71 silent case
H3650 SILENT/HTDI/512M - AGP 8x/ ATI/ 3650/ 512 MB/ DDR2/ 128 Bit/ GPU: 725 MHz/ RAM: 1000 MHz/ TV-Out, HDTV-Out, HDMI-Out, 2x DVI/ Features: HDCP/ passiv
Windows XP64 SP2
probably RME Multiface PCIe, some TI Firewire 800