I was looking into building a server to use for web hosting/file-sharing/backups. I looked at some of the Xeon processor and motherboards but the cost adds up quickly. If I were to use say a core i7 what would be the difference in performance (since i7 dosnt have ECC)
AMD will release a 12 core and 16 core opteron very soon,might want to wait for it.
AMD already have (and have done for quite some time) 12 and 16 core parts (somewhere in 2011) in all flavours from K10, Bulldozer and Piledriver based. They are just as expensive as any other server part.
You're way over judging what you need for Web Hosting, file sharing and backups.
Although web hosting can be heavy use that's only really when you get in to larger sites or sites with dynamic content (aka pages that can't be pre-loaded or cached.... like forums)
File sharing and backup's doesn't really consume any processing power, unless you are planning on using something like ZFS. (not really suitable for file sharing purposes, great for backups)
Again ECC would be nice (when dealing with ZFS) but not really needed.
You could easily get away with something like a simple Quad core with like 8GB of RAM. Using a board with enough SATA connections for what you require (unless you plan on using a hardware RAID card)
Anyway, I can't really suggest stuff without a budget. Soooooo.... What is the budget?
the Xeon E3/H87 mobo is ALOT cheaper than an i7/Z87 chipset...
http://pcpartpicker.com/p/1ZlMO
vs
http://pcpartpicker.com/p/1PAsI