at least maxing out gigabit
Software or storage is likely to be a bottleneck. Are you planning on maxing out gigE with Samba?
running active directory with roaming profiles for everyone so their 'My Documents' stays on the NAS
Can't you do this with Samba? I've never done it but I assume this is a common requirement.
I spent a few days trying to get this to work, but it didn't want to talk to Windows 7 domain clients, and it implicitly requires a reduction in network security. Since I operate an open wifi that anyone can connect to I decided to buy Server 2008. So I will be using that.
I think the best value route is to get a CPU with integrated graphics to do the 1080p decoding, so that means I must at least get an i5.
Any modern GPU can do this. Maybe I'm missing something... what exclusive video decoding feature are i5s supposed to have? I've never heard of it.
You're missing that I've chosen at least an i5 because this series has AES-NI. The more I've looked into it because you all prompted me to reevaulate my decision, the more I've realised the price difference between the range is so small it'd be silly not to get the better one. Although I am probably going to settle on the i5-2400(S?) now, rather than the 2500K.
running in a VM
I believe you need to be very careful about the chip you buy. My recollection is that not all of them are equipped to run virtual environments. That being said, maybe you should look at the 2105. It has the 3000 IGA.
If this had AES-NI, I'd have got that. Since I can get a second hand 2400 for the same price as an i3-2105 I may as well get the 2400.
Maybe someone has already addressed this, but have you considered waiting for the Ivy Bridge. The TDP of the new 4 core Ivy Bridges is 77 watts compared to 95 watts for the old 2500K... and they are faster on top of that. They even work on most of the boards that run the 2500K. The new 4000 IGA is supposed to be extremely powerful. Materially more powerful than a Radion 5450.
With that and an SSD, it is hard to believe you will run into any hardware bottlenecks.
Yeah, the system will boot from a 30 GB SSD. I have thought about waiting for Ivy Bridge and it is a possibility, although it would probably make the build more expensive because it'll be new and there will be a high demand for it.
deed02392: How many users are you going to have that you think you need a domain? If you just want to redirect my documents you can do that manually just fine for a few users. You don't need a Windows server, Linux running samba or a Windows 7 desktop would be just fine.
There's my parents, myself, two siblings and a lodger. But the big reason I want to go for it is so everyone can login to everyone elses machine without having to bother creating multiple accounts between them all. If we can borrow each others computers when we need to and still get up our 'My Documents' that'll be grand. There's also the fact I've already bought Server 2008 and want to implement it.
If you want to max out Gigabit then you should run your file server on the bare metal. If you are serving from Linux then make sure you have an up to date samba version that has SMB2 support.
I will be serving from Linux and the Windows Server will refer to the Linux samba shares. Server 2008 won't be hosting any users data but simply acting as the domain controller, DNS server and DHCP server.
You want a domain controller that's also a NAS and also a HTPC?
Your requirements don't make any sense. I think your in way over your head.VT-x CPU list
VT-d is Xeon only.VT-d needs bios support through the mainboard. You need a server board with C20X chipset. SOME Q67 boards have some level of support, but they're not meant to be used in servers.
You should check the boards at servethehome for more information.
Why do you insist on a single machine for several workloads so diverse?
Get a cheap pre-configured server like the HP ProLiant ML110 or PowerEdge T110 II as a domain controller. You can get professional support for these.
I don't need/want professional support, given how small the network is any issues I'd like to figure out myself and learn about how Windows domains work.
Get a powerful NAS for storage: Thecus N7700PRO
has a Core 2 Duo Notebook CPU and great performance, you can get a 10GB ethernet controller as an option. But to buy the NAS from the same vendor as the server is probably the better idea (hint: support).
Get a set-top box for decoding, WD TV, Apple TV,...
Putting all those workloads on a single machine is asking for trouble. I wouldn't want to troubleshoot a solution where all those tasks are put on one machine. You need a professional solution and you're asking advice here, that should tell you something. There's companies out there configuring and selling servers to SMBs, maybe it's time you talk to them.
I don't see why I need a professional solution. The reason I'm going for an all-in-one solution is cost. I'm not exactly loaded and there is limited room behind the TV where all this needs to go (don't want to run ethernet cables everywhere). I know you are going to think I'm being unhelpful by not taking all your advice but I do appreciate everything you've told me. So far it seems like you've helped the most with that but there seems to be some issue where people have assumed I haven't already done enough research into what I should choose regarding the CPU. Budget is a big constraint, as well as some minimum requirements (e.g. AES-NI).