Currently I have two monitors that are running pretty well on my Sapphire 4870 with 512 Mb. I don't need crazy performance out of my GPUs because my gaming is for the most part is limited to TF2, Left 4 Dead, and Bioshock. My current monitors are a 23" running at 1920x1080, and a 19" running at 1280x1024. My plan is to probably add a second 23" running at the same resolution.
Here are my current system specs:
CPU: AMD Phenom 9850 Black Edition
Motherboard: BIOSTAR TFORCE TA790GX A2
Memory: 8 Gb of OCZ Reaper
GPU: SAPPHIRE 100259L Radeon HD 4870 512MB
I do have an open slot on my MoBo where I could squeeze in a second card, and I understand that it will probably be necessary for a 3rd monitor.
I've been toying with the option of upgrading all of my internals to the i-5 2500k, p68 board, and new card(s) so that may be an option, but I'm not quite sure if I'm ready to drop the money on that yet since my Pc is still doing just fine.
You want to run a triple display with two different screen resolution?
Also if you run 5760x1080 you going to need a crossfire setup and Then a better cpu and id recommend a z68 motherboard because you can overclock and if your graphics card fails you could use integrated graphics till you get a replacement