760G - Low end, has integrated graphics but for the price they are it's not really worth considering.
770 - Budget offering but has very similar performance to the 785/790 chipsets. Is probably the best option if you don't want dual graphics, if you do then the best it can do it x16, x4 like the old P35 chipsets.
780/785G - Similar to the above but has integrated graphics, which can come in useful if you're not using a dedicated graphics card. If you are then i'd say skip this and use a 770 for the sake of the added power draw etc.
790X - The 790GX chipset but without integrated graphics. Is alright for most things, does x8, x8 crossfire if you want that.
790GX - As above but with some more powerful integrated graphics than the 78*'s.
790FX - Current top end, x16, x16 crossfire. Some will support the x6 processors with BIOS updates when they come out.
And to be coming soon:
870 chipset - cut down version of the 890 chipset, can possibly do x8, x8 crossfire but should have better performance than the 7** series and has a 14W TDP.
890 chipset - to be the new ultra high end, better performance and low power draw. Will support Thuban out of the box.
