<p>What would be the best WPF control in C# (VS 2008) that you can place on a form that would allow you to do drawing similar to the "Paint" function for the CWnd class in C++?  Also, that could display bitmaps, have a scroll bar, and the ability to accept user inputs (ie. MouseMove, Button Clicks, etc...).  Basically all the functionality of a CWnd in a control on a WPF form?</p>

No.  As of version 2.0, the .Net framework has it's own little filesystem setup for security.  Administrator or not, .Net apps won't do certain things if they aren't running from a 'trusted' location.
Just about anything on your local hard drive is trusted, but (and supposedly they fixed this for 3.5sp1) even the local intranet is
not
trusted, so most .Net desktop apps will fail to even start if they're sitting on a network drive or share.
You can change the configuration on a machine so it will allow apps from that zone, but it has to be done for
every
machine that's going to run the application, which breaks a common corporate deployment scenario.
From an ASP.Net standpoint, it also means that certain activities require more 'trust' than others.  Sending e-mail, for example, can cause exceptions if not set up correctly.