Why the dual Xeon 5405s on SBS instead of the terminal server running 9 virtual machines? I would've probably switched it around. Also, put more RAM in the SBS server. TBH, SBS really needs a minimum of 12, with a recommended of 16GB. Another thing about the terminal server, isn't cheaper and less resource intensive to just use a terminal server with RDS licensing. I believe XP licenses are more expensive than an RDS CALs. Also kinda defeats the point of a Terminal Server with shared resources when you're running six virtual machines that are using separate resources.
Info Overload Below (Read only if you're bored.)
Maybe on the next one. Get a dual LGA 2011 motherboard with two E5-2620 (12 Physical, 24 Logical Cores) or two E5-2650 (16 Physical, 32 Logical Cores). There's a $1600 price difference between the two. I'm pretty sure the 6 cores would be more than enough. 10 Logical Cores to SBS 2011 and 14 to the Terminal Server.
Server 2008R2+SBS 2011 with the 1+1 licensing you can install a Server 2008R2 base and add the Hyper V role and add the SBS 2011 and Server 2008R2 as guests. I know you like XenServer, but I think HyperV and ESXi have more to offer. I opt for Hyper V for the simple reason that it interfaces well with BackupAssist.
32GB of RAM or 48GB. Probably 16 for SBS and 16 for the Terminal Server. 32GB will run you about $250. You can easily add more since there are 16 RAM slots on these mobos. If you want super speed, run a RAID 10 of 128GB SSDs. 256GB to the guest Operating System, Terminal Server, and your AC Database. I'm suggesting RAID 10 over RAID 1 not for speed but for the greater redundancy and that SSD price is essentially linear. A 128GB costs nearly half as much as a 256GB drive so why not just get even more performance. Your thin clients will run much faster. Give about 120-140GB to SBS, the rest to the terminal server and AC. Use SBS wizards to move user data to the second array of storage drives.
Keep your data on a set of RAID 10 500GB RE4 drives which will give a 1TB usable capacity for data storage. Most offices don't exceed 100GB between all of their computers. Enable folder redirection so all of the user data will sit on the second 1TB array. Make sure you get one of those 8 Port RAID Cards with SATA 6.0 GBPS ports.
The way I figure it you could use something like 6 or 8 Seagate SAS drives that will cost you $500-1000 more than the SSD+HDD setup mentioned above. Or you could use 8 WD RE4 drives in a single RAID 10 or two RAID 10 arrays. The price would be the same, but the capacity would be double. But like I said, most offices don't exceed 100GB between all of their computers and they would be worlds apart in terms of speed.
Another side note about the network. Since your Terminal Server and SBS installation would be on the same box, it'll be passing through the internal network with virtually no lag. I highly doubt you'll find a major OEM that can do this build since most of them haven't even caught on to the LGA 2011 socket. They would also murder your wallet. Probably charge you double or triple the actual cost of the hardware.
The server I'm specifying here could feasibly run 30-50 users.
.png "ACUF Donor I")
