OK, here's what I think. C# programming for WIndows is MUCH better than C++ on the GUI scale. Very fast, and the object-oriented aspect of C# is just wonderful. I am an OOP fan by the way. For speed, graphics, or anything that gets "nitty-gritty" so to speak, ya gotta have C++.
Another aspect that you have to realize is ability to distribute. C++ is VERY portable. Most machines can run it without any modification. C#, on the otherhand, isn't very easy to distribute...yet. The target machine has to have .NET installed and most likely has to be Win98, WinXP, Win2000 to run (people are saying that they are getting it run on other OS's too). I've also heard (again, not sure that its true) that you can only develop for C# in WinXPPro (please don't jump on me if i'm wrong!).
ANyways, that's my opinion.