I recommend the Mach Speed. Although I have never heard of them before, the options that the MS board has, outweigh those of the DFI.
One thing in particular is the DFI board only supports up to 533MHz FSB, while the MS supports 800MHz. Although the Celeron D in either case only has a FSB of 533MHz, getting a mobo that only supports 533MHz strictly limits future expandibility.
I normally wouldn't recommend either one of those, but if you are stuck on those 2, I'd go with the MS.
If you want opinions on other alternatives, post back with a budget, and I'll see what I can find for you