There is no need to bother with a server motherboard and CPU if you only intend on having one cpu and 4GB of ram. For this setup, even 500W would be overkill. Also this board does not come with integrated graphics, so you would need to purchase a card aswell. Any cheap card will do. Why the big heatsink? Do you intend to do a whole bunch of overclocking? CPUs come with stock heatsinks. What exactly are you going to be using this server for anyway?
Edit: sorry I didnt see you intended to add more ram and another cpu in the future. I'm sure 600W would be fine. That's to be safe. I'm sure someone else will say you can use less. Of course I'm just assuming that you'll double the ram and add one more hard drive when I guess this.
I would go for a 7200rpm drive for sure. Alot of times you can get away with a plain desktop MOBO with built in graphics, seeing visuals are insignificant. I would also recommend Ubuntu because it is free and I have had better luck with that than any MS server software. Ive done 3 servers, and most depends on what your sharing and to how many computers.
my biggest problem is my budget, i want to keep it around 1500 usd and make it upgradeable in the future. I am going with a different mobo (asus dseb-dg) that is a really good price currently on newegg. Is a faster hard drive really necessary for a server application? Or should I add more memory. I will be hosting mostly many forum sites, this is one of my sites (puroeuro.com). What should I change to optimize performance for these kinds of sites? I am not going to host any large files because that is illegal and my site is legal. It is a music directory and not a file hosting site.
Ahh... so this is mission critical then? Well in that case (considering your $1500 budget), I highly recommend a hardware based RAID 5 set up with a mid range Nehalem Xeon (possibly 2P). If possible, a SSD like a X25-M G2 will offer great access,seek,etc time benefits to a server based workload. Don't get a 5900 rpm "Green" drives, they are too slow imo.
@OP: Mind listing about how many users you get at the same time? What about the rest of the system (esp. the network side)?
@OP: Is this a file/web server? Or some other type of server? If it's a file/web, a fast HDD/SSD will really help.
I have a WD EACS sitting in my old computer so I am going to put it together with the 640gb wd hd because I do not think I need a lot more than that. My biggest problem is finding a good cpu coole for the lga 771 that is not very expensive
LGA771 is dead already, and so are expensive/hot FB-DIMMs (thank goodness that's over).
A simple site hosting server will only need to be UP with a quad. 2P (LGA1336 territory) is useful if you intend to hire out VPS using VMs. For todays UP platform the LGA1156 Xeon X3440 (needed for ECC support) fits the bill nicely.
[EDITED]You'll need 8GB RAM (or more) for sure with that you're doing.