The main difference between the 920 and the 860 are that they use different sockets, different chipsets, have different memory controllers and the 860 has integrated PCI-E lanes.
The 920 is socket LGA1366 and uses the X58 chipset
The 860 is socket LGA1156 and uses the P55 chipset
The 920 has a 3 channel 1066 memory controller
The 860 has a 2 channel 1333 memory controller
The 920 does not feature integrated PCI-E lanes, everything is contained in the chipset, which makes the motherboards more expensive. The X58 supports full bandwidth multi-GPU (2x16 lanes)
The 860 features 16 PCI-E lanes, so less is contained in the chipset, and the motherboards are less expensive. The P55 platform only supports half bandwidth (2x8 lanes), the performance differences between multi-GPU setups on each platform should be minimal though.
I would go for the 920 if it is the same price as you are getting a better features platform which far greater support for upcoming high end products.
i hear ati sucks with intel and is good with amd and that i should go with nvidia, but id like to hear from you guys.
That's very strange because Crossfire is better supported by Intel than Nvidia and AMD/ATi have been much more willing to work with Intel than Nvidia have. Definitely look up the HD 58xx series.