<p>I need to write a digital oscilloscope type application.  There are many great static graphing controls out there, but I need something that can graph 16 traces processing 4000 samples per second.</p>

<p>Is anyone aware of a high speed graphing control for .NET?  I'll even take MFC since that can be wrapped into a .NET control.</p>

<p>Thanks for the help!</p>

Have you looked at
GraphViz
? I've seen it used in oscilloscope applications, but I'm not positive it will handle the speed you're looking for. GraphViz doesn't take a 'live feed' of instructions like some of the GDI+ controls I've seen.
There are some
.NET wrappers
for it
.