Update: See the Comments for follow-up.
I contacted Sales via chat looking for a computer recommendation. My requirements were simple: A Sandy Bridge (second-generation) Core i5 processor and the ability for 3 simultaneous displays.
The agent said that a Radeon HD 5670 video card would work for me, and gave me this link. He may have said that I needed a 5770 and linked a 5670, but the Dell chat system removes all model numbers from the chat logs.
He then gave me a quote, and I bought the complete quote, even though it had some items I didn't want. (I didn't want the security software and didn't need the speakers, but a later agent who tried to take them off wound up with a much higher price for less, and apologized, "I'm sorry the promotions changed").
Similarly, I didn't argue much concerning specific card models because different cards have different features, and your configurator gives very little detail about the actual cards. I mentioned that a forum post said that the system will only handle three displays if one of the ports is DisplayPort, and the agent said that the onboard video includes DisplayPort and that I can use them together. I pointed out that the pictures do not indicate DisplayPort is onboard, and he responded, "yes, but it is guaranteed as included."
The agent gave me a quote, and I bought from the quote provided. I realized only later that the quote only had a Radeon HD 5450, not the 5670 he had originally specified. Again, since the limitations are, to my understanding, based on offered ports and not the chipsets, and since the configurator gives zero information as to the ports or any other specific features of the cards offered, I am relying on the agent's expertise.
When I got the computer, I set it up. And had difficulties getting three displays to work. Both onboard ports were capped and disabled in BIOS; presumably there is a reason for this. I expect this is due to the system design; it's quite common that onboard video does not work with an add-in card. But the onboard video did not have DisplayPort anyway, only HDMI and VGA, despite the strong assurances of the sales agent. The add-in card has HDMI, VGA and DVI, and despite being told that it would not support three displays, I tried anyway, unsuccessfully of course.
Then I contacted Technical Support via chat. And was told that three simultaneous displays requires "Ati 5770". Nevertheness, he connected to my computer and played with my system settings for the next hour, and of course ended the same as it started: only two displays would work at a time. Any two of the three, but only two.
His solution: He will send me a DVI splitter, which will let me connect two single-link DVI monitors to the dual-link DVI port. Which means I am limited to single-link displays and separate audio cables. I was going to use a DisplayPort to HDMI adapter which would pass audio, and would like the ability to go to a higher-resolution display later, such as the Dell 3008wfp or U3011.
In summary, I seem to need an ATI Radeon 5770 card to meet one of the two only requirements for the system. But the sales agent linked a 5670 which he insisted would work. And he then quoted a 5450. And their "solution" is to use a splitter rather than actually fixing the problem.