Go for the DFI if only you'll be using BH5/6/CH5/UTT ram as that's the only ram where you'll need the high Vdimm of 3.3V+
But don't go UT-D, go for the newer Venus boards which are far improved over the original SLI-D\SLI-DR\UT-D as the 4V issue* has been fixed so you're unlikely to kill your motherboard or RAM using the 5V rail.
If you're going for the 2GB sets of memory based on samsung chips then, the Asus A8N32 will do perfectly. It has Vdimm all the way upto 3.2V (and its far more stable than on the DFI UT-D) which is more than enough for the DDR500~DDR600 modules and the like that only need 2.6~2.9V max.
HT speed on these should be good for 350MHz (3XLDT) which is more than enough for any multiplier. (3.15GHz with 9X and well its obvious for 10X)
Not sure how easily available the Venus boards are of the DFI SLI-Expert so I'd lean towards the Asus A8N32.
The bios is by far the leat friendliest, but it has most of the useful features.
And its 2x PCI-e 16
