>We're developing a very large app ... for sale, not an inhouse product. It's written entirely in C#. I know that some people are saying that C# is better for server-side stuff and VB.NET is better for UI stuff, but I don't agree. My point, again, is that *I* think it still comes down to personal preference and/or the background of your developers. Others here will disagree with me.

I think some of these opinions are based on the future directions of each language as well. In Whidbey for example, VB will have edit-and-continue in the debugger while C# will not, which is often useful for UI/form development. From our recent world-wide VFP survey, more VFP developers are using VB .NET over C#.