I've done .NET work on my I8600 (same as the D800) for nearly two years now. Video card makes little impact on this; max the CPU, RAM, and HD speed (7200 is a must). This is actually my primary reason for an upgrade, as my current machine is just getting too slow with all the applications I run. Duo core should make a substantial performance improvement for me.
Widescreen helps a lot to show all the VS windows and panels. This is the only place where I see graphics acceleration helping; the effects in VS to show and hide panels are more fluid on an accelerated graphics chip. But if you have a screen where you see everything, its not as important. However, I game on this machine as well so it is important to me