I just want to put in a plug for Appro dual opteron servers, in case anyone is still looking for a solid dual-opteron solution. Anandtech did a glowing review of Appro servers a while back, and I've been using them since 2000. My last server ran for 5 years straight without even a blower going out :) They're currently offering a 1U and 3U version. Not the cheapest servers out there, but very solid.

http://www.appro.com/product/opteron_main2.asp

I would use a SAS 15K drive for the database. :)
It burns SCSI (in stats) like the prairie fire.

If you guys use colocation, you should definitelly go with Dell. They have a dual opteron model, SC1435. Many people at WebHostingtalk know that Dell servers are better compared to the SuperMicro custom builts for example (and cheaper also).

Ya, I like Dell. If you know what to buy from them (specific parts), you will be very happy. :)
My coding corner

Another important question to choose Dell is the DRAC/KVM the drac save my life many times during working travels :D
I have xeons poweredge 1850 (for 3 years) and another 1950 (now)