the 680i isn't that great of a board for the price... don't get me wrong.. its a nice board and has a lot of nice features (6 SATA Ports and Dual Gigabit Ports)
but p35's are overall cheaper and overclock better... heck even the p35-ds3p is cheaper than that... and that has Crossfire instead of SLi (but who really needs it anyway)
EDIT: did you plan on using your two 7800gt's for SLi on those boards?