If I've narrowed it down to the Foxconn or the Gigabyte, I see two differences.... the 965 vs. the 975 and 3 PCI vs 2 PCI. The Foxconn has only 2 PCI slots, BUT it also has 2 IDE channels so I wouldn't need to add an additional IDE controller, so that amounts to the same thing, unless onboard IDE offers and advantage over PCI IDE....
Someone said 975 works better with the e6600? I think the 975 offers stuff like Crossfire, but that's not of interest.
Then there's the MSI -- that also has 3 PCI slots, but only 1 IDE channel, but has SLI (not sure what that is, but I think it's a video Crossfire like thing that also isn't of interest.)