ECS is good from a price standpoint and that's about it. Build quality varies from board to board (I've gotten some that were fantastic and some that were DOA) and they generally don't have overclocking options worth discussing. If you're planning to OC don't buy ECS, go for Abit, Gigabyte, ASUS, or DFI instead.
Regarding dual video cards, you can run two AMD/ATi cards in Crossfire on any Intel chipset boards (P35, P43, P45, X38, X48) that have two physical PCIe X16 slots. Note that the X38/X48 boards have full x16/x16 bandwidth while the P35's are normally x16/x4 and the P43/P45 are x8/x8.
If you want to run two nVidia cards in SLI you're stuck with an nVidia chipset board (680i, 750i, 780i, 790i). These boards can be quite expensive so make sure SLI is what you want before buying.
EDIT: And you'll get a lot more responses posting in the Motherboards forum instead of Video Cards & Graphics.