Almost identical to the IC7, the IC7-G also features Gigabit LAN and four SATA connectors. Three fan headers on the board allow for the heatsink fan, case fan and an auxiliary fan, which is good for tweakers. Side-mounted IDE ports stop cables draping over other peripherals, improving cooling.
You do pay a premium for the extra SATA and Gigabit Ethernet though, so if you're not going to use it, then go for the IC7.