I obviously can't comment since I use both! But... I also agree with JB, if you're a C++ person, then DGDK, otherwise if you're eager to use Visual Basic or C#, DGDK.NET performs on the same level.
I will add that you may find setting up DGDK.NET easier since there does tend to be complications for a small minority of people who use the DGDK (C++) toolkit, but that's normally associated with minor differences in each developer's system and availability of libraries etc.
It's your choice:
Door No.1 - DGDK (C++) Compatable with C++ Express version available from Microsoft, and of course the bulk commercial versions.
or
Door No.2 - DGDK.NET, usable with all of the Express development tools available from Microsoft.
Paul.
"This is Big Brother, could Ian please remove his head from the oven, thank you!"