You know NCIX does price-matching? So say other stores sell a product for less, ask NCIX to price match 'em. You may even save some money on shipping or gas or transit fares if you buy everything from the same store.
Why use desktop parts to build a server rig? I beg to differ. I'd use server parts to build a server. Why? They're more reliable and maybe more expensive. Speed isn't your primary concern. Stability is. No matter how much faster the i7 2600k is than a Xeon, if it crashes, kiss your work day goodbye. FWIW, my i5 2500k with Turboboast on might have caused a crash in a cpu-intensive RTS game back to desktop. At least, after overclocking. FYI, Xeon gets the smaller nm before desktop chips. Xeon Westmere has had 32nm before Sandy Bridge. There's a cost-saving option called AMD Opteron with 12 cores for over $1000 or 8 cores for $280. Intel wants $1000 for 6 cores. You don't say your budget. I'll assume $1000ish. Another way to get more cores is to go dual processors with a total of 8 cores. Yes, there are mobos for dual cpus.
Now onto storage. Go with enterprise-class hard disks. They're made for servers & generally have 5-year warranty, compared to 3 or 1 for desktop drives. I'd recommend a RAID 5 setup with 3+ same-size hard disks. SSD is pointless if you don't have stability. Speed is not everything. If your applications require much disk access, I think you should re-code them to offload the usage to the client side. I don't know exactly what you're developing. I'm talking web programming.
"RAID 5 (block-level striping with distributed parity) distributes parity along with the data and requires all drives but one to be present to operate; drive failure requires replacement, but the array is not destroyed by a single drive failure. Upon drive failure, any subsequent reads can be calculated from the distributed parity such that the drive failure is masked from the end user. The array will have data loss in the event of a second drive failure and is vulnerable until the data that was on the failed drive is rebuilt onto a replacement drive. A single drive failure in the set will result in reduced performance of the entire set until the failed drive has been replaced and rebuilt."
If you don't have a plan B for data warehousing, think about it. Something as simple as a ESATA enclosure with a 1TB drive is better than nothing.
https://secure.wikimedia.org/wikipedia/en/wiki/RAID
How much ram is needed depends on the OS. For 64-bit os, 8gigs+. Otherwise, 4 gigs. No, the server ram doesn't have heatspreaders cuz the server will most likely not be upgraded at all other than storage or it'll be an overhaul.
http://www.newegg.ca/Product/ProductList.aspx?Submit=ENE&N=100008493%20600048535&IsNodeId=1&name=Westmere
http://www.newegg.ca/Product/ProductList.aspx?Submit=ENE&N=100007628%20600007999&IsNodeId=1&name=Dual%20LGA%201366
http://www.newegg.ca/Product/ProductList.aspx?Submit=ENE&N=100007602%20600003459&IsNodeId=1&srchInDesc=Enterprise&name=SATA%203.0Gb%2fs&ActiveSearchResult=True
http://www.newegg.ca/Product/ProductList.aspx?Submit=ENE&N=100007951%20600006050&IsNodeId=1&name=240-Pin%20DDR3%20SDRAM
As for case & psu, it will depend on your mobo selection. If the mobo is ATX, the case & psu must be ATX.