With the motherboard you chose any PCI express x1 card should work fine. Getting a sound card for a workstation used to be a problem since most server motherboards will only support 3.3V PCI cards, at lot of consumer grade PCI cards use 5V signaling for better backward compatability. For instance all turtle beach sound cards are 5V and will not work in server/workstation motherboards (PCI 2.3 or 3.0). So, I ended up getting a USB sound blaster when I built my last workstation.
You need to make sure the power supply you choose supports the 2x 8 pin motherboard power connectors. Basically EPS12V with 2x 8 pin MB connectors or enough 4 pin ones to fill in.
Your case must support 12"x13" motherboards.
It looks like you do not have the heatsink mounting issues that exist with the socket 771 xeons (you had to mount the heatsink to the case, so you had to pick a case which supported this). The picture here shows that the heatsink mounts to the motherboard now. Not sure if the 1366 xeons use different heatsink dimensions from the i7s. They looks the similar in the picture...
FB-DIMMs would get really hot so I had to install memory cooling fans on my workstation builds using the DDR-II FB-DIMMS, but it looks like this MB is using ECC/registered DDR-III which should not have as much heat issues. You don't have the FB processor which is where most of this heat generation came from, but you do still have the registered part which may generate some heat.
Server boards also tend to have a severe deficiency in USB ports and USB headers, but USB hubs are cheap. My latest one has 2 ports on the back and one header for two on the front.
Can you check this config to see if everything would work?
Would appreciate your help, before placing the order.
Microsoft Windows Vista Home Premium SP1 64-bit for System Builders
CORSAIR CMPSU-750TX 750W ATX12V / EPS12V SLI Ready CrossFire Ready 80 PLUS Certified Active PFC Compatible with Core i7 Power Supply
BFG Tech BFGEGTX2801024E GeForce GTX 280 1GB 512-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card
Western Digital VelociRaptor WD3000HLFS 300GB 10000 RPM SATA 3.0Gb/s Hard Drive
Thermaltake Armor Series VA8003BWS Black Full Tower Case w/ 25CM Fan
2x Intel Intel Xeon E5520 Nehalem 2.26GHz LGA 1366 Quad-Core Server Processor
TYAN S7002WGM2NR-LE Dual LGA 1366 Intel 5500 SSI CEB Server Motherboard
CORSAIR XMS3 12GB (6 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10600) Desktop Memory Model HX3X12G1333C9
Creative Sound Blaster Audigy SE 7.1 Channels PCI Interface Sound Card
OK, where to start, first off I think the supermicro MBD-X8Da3-0 motherboard would be a better choice, it has the 5520 chipset which I think is a better choice. Secondly, there is no compatability between core i 7 heatsinks and fans and Xeon ones, they are not interchangeable. The heat sink does not attach to the motherboard but to standoffs mounted below the cpu's, if your case is big enough(full towers only need apply) but if there are no holes, you may need to drill and tap new holes for both chips. As for power supply, go directly to either the 1000watt or 1200 watt corsair power supply or an equivelent that has both the 8 pin connectors, to do otherwise would be a dissaster. When you spend that much money to scrimp here would not be good.As for Vista, 64 bit is a must with that much ram but there could be a problem with the dual cpu's and Vista, I think that Windows 7 ultimate 64bit would be the way to go as it is better at multithreaded support. Remember any Xeon 5520 and above has for the first time built in hyperthreading technology and that means 8 physical cores and 8 hyperthreading cores. See if you can borrow a copy of Vista 64 bit and try it, you don't have to activate it just to do a sort of breadboard test, and if it does not work wait for Win 7 64 bit in October. Hope this helps, all the other equipment sounds good,