There is a little bit of confusing and unknown territory still with the latest AMD FX bulldozer processors when it comes to backwards compatibility. It was said that these FX processors (including the latest AMD FX eight core processor which combats performance-wise with the Core i5-2500k) would work in any motherboard that is AM3. However, that is not the case.
Upon its release, AMD clarified that the only motherboards that would have true support for Bulldozer processors would be motherboards with an AM3+ socket with a 9XX series chipset. This means either a 970, 990X, or 990FX chipset AND an AM3+ socket. While theoretically you can still drop in a Bulldozer processor to a motherboard that has an actual AM3+ socket, in reality the BIOS support is not confirmed and you could very well not have a compatible system. The bottom line was any AM3 socket motherboards would NOT support the new Bulldozer processors as they have a different pin-out.
I've personally built many AMD and many Intel systems for a variety of applications and uses. One thing I've liked more about AMD is they seem to offer a little better "bang for your buck" as you can get great performance at a cheap price, and they tend to run cooler than similar Intel systems. However, if you're aiming for the best performance and price isn't really an issue, then I'd recommend a high-end Intel such as the Core i7-2600 or i7-2600K. They also just released the new flagship core i7-2700K!
Nothing (yet) in AMD's stables can quite keep up with the performance of the Intel flagship models, and anymore the Intel prices are not that much more than AMD prices.
As I've mentioned before elsewhere, one thing I would not skimp on would be the power supply. It's the heart of your computer and can make or break the rest of your build! I've used a lot of Antec High Current Gamer series power supplies as well as Corsair power supplies, which are the elite highest quality on the market. Get something with more power than you need now, as you may decide to upgrade or add more to your system in the future.
Even if you are planning to do really intensive graphics, unless you are planning on hardcore Crysis crunching or wanting to do GPGPU rendering for a medical imaging facility, there's no need to spend all your money on a graphics card. Even a mid-range $100 to $150 will have way more power than you will ever need in your day to day tasks. Again, unless you are doing some major gaming, you will see absolutely no benefit in picking a $500 video card over a $150 for design work.
If you're dead set on getting the best quality video card, just get a mid-range Professional graphics card. I've used several nVidia Quadro cards in the past and while they are expensive, they are unbeatable quality for design work. They can be expensive (expect to pay between $150 to $250) but you don't need ANYTHING more than that.
Save the money from that video card and put it to use on either more memory (which is incredibly cheap right now!) or monitors. If you're doing design work get an IPS panel display if you can. The Dell U2412 is the updated version of an award-winning and well received high quality monitor from Dell. For an IPS panel display you cannot beat the price, often on sale for as little as $320. Many IPS panel displays are going to be in the $1,000 price range or more!
Additionally, get some aftermarket CPU cooling. The included stock fans are never enough to really keep up with demanding tasks on your processor, which can mean your system is constantly hot, and can even lead to decreased expected lifespan of your computer! The Cooler Master Hyper N is a great CPU fan, we've used dozens of them and they are great from your entry level system to a high performance design workstation, and at around $35 they're not expensive but well worth the investment!
For an operating system, Windows 7 Professional 64-bit is probably going to be the best way to go. There's nothing in the Windows 7 Ultimate that you're going to need that Windows 7 Professional doesn't already have and you can save your money there for other things. Purchase an OEM license when ordering hardware to save quite a bit on costs if you plan to do this yourself.
Of course, if you don't really have the skill, understanding, or time to do this assembly yourself, then I'd recommend giving Casey with SignBurst a call. He builds custom systems specifically for the sign and design industry, and he is an expert at what he does.
