Custom Build Workstation Help!

The Intel Xeon (the E7 family) is designed for servers. If you are looking to build a PC, the Core family is the way to go. Do keep in mind, however, that the Xeon family is compatible with more than one CPU on one motherboard, while the Core family is not. The Core i7 Extreme Edition is an incredibly fast and powerful processor; and with a budget of $6,000, it should be good for your needs.

If you are running four monitors off one computer, then yes, SLI is the way to go. You may consider buying a slightly less expensive card and running three-way (or even four-way) SLI.

The Xeon family is compatible with ECC memory; the Core family is not. Again, Xeons are designed for servers, which need to be incredibly reliable, and ECC memory increases reliability.

I'm not sure it makes sense to spend lots of money on multiple SSDs. You might be better off getting, say, 3 2TB HDDs, (or 2 3TB, or 3 3TB,) to put in a RAID array.

Also note that most motherboards come with only four DIMMs (RAM slots), meaning that they are compatible with UP TO 32GB of RAM. You can, however, find motherboards with 8 DIMMs, making them compatible with up to 64GB of RAM, for not an extremely increased cost. If you go with a Xeon mutli-CPU configuration, you can get up to 64GB of RAM, but that option is significantly more expensive.

As far as the answers to your questions:
1. The socket is only as good as the processor that goes in it. The socket is only important for which processors are compatible with the motherboard (which obviously matters); what's more important as far as the board goes is: What is the chipset? How many PCI slots are there? How many RAM slots are there? That kind of thing.

2. The Core i7 Extreme and the Xeon are somewhat similar processors. They are both very high-end, and both very expensive. I pointed out some key differences already. Again, i7 Extreme is more geared toward performance, while the Xeon is focused on reliability.

3. Based on your line of work, it is true that your video card/GPU is probably more important than your processor. HOWEVER, DON'T go for a high-end video card and get a cheap CPU to go along with it. Doing so will force the processor to work harder than it is capable of doing, and can cause your machine serious damage.

4. As I said earlier, no. However, an i7 Extreme should be just fine for what you need (after all, it can handle 12 threads at once and its cores are fully unlocked).

Basically, I vote you go for the i7 Extreme edition; it will give you great performance at high speeds. Also, don't forget that you also have to buy other essential components, like power supply, CD drive, case, and CPU cooler.

Also, if you're doing photo work, make sure to pick up a multi-card reader. The nicer ones cost only $20, and they will allow you to use SD cards to work with any photos taken on cameras.

If what I've said has been helpful, please consider picking me as the solution

http://ark.intel.com/compare/63696,70845
These are probably your best CPU options