The Asus has Firewire as well. The DFI has 10 USB and so does the Asus.
Asus: Two PCI-Express x16 slots with SLI support at full x16, x16 mode, one PCI-Express x4 slot (supports x4 and x1 add-in cards) and three PCI expansion slots;
DFI: 2 PCI Express x16 slots, 1 PCI Express x1 slot, 1 PCI Express x4 slot, 3 PCI slots
So basically, the DFI has one more slot; a x4 and a x1 PCI whereas the Asus combines them. Have you seen any x4 or x1 devices on the market? I haven't (except maybe a wireless nic card and the asus also has a model with built in wireless nic, DFI doesn't).