This handy Channel9 post shows how you can create XML Web services using Visual C# 2005 Express Edition Beta 1. I have gotten questions like this and I wanted to explain the difference between Framework support and tool support.
C# Express has full access to the .NET Framework. What that means is that you can create XML Web services using C# Express, you can can use ClickOnce deployment, and you can even access remote data from your favorite database. C# Express does not have full tools support for each of those things.
- For Web services, it means you'll be able to write the code for your Web service using C# Express, but to run it you'll need IIS and you'll have to register your virtual directory manually. (Note: You should really be using Visual Web Developer 2005 Express for Web development as it has a built-in lightweight Web server). You don't get IDE support for Web projects in C# Express.
- For ClickOnce, at least for Beta 1 (Note: We've added ClickOnce deployment to Express for Beta 2), you'll have to manually create XML manifest files, strong names, and all the goo that the IDE does for you automatically. You don't, at least for Beta 1, get IDE support for ClickOnce.
- For data, it means your data access code will be manual ADO.NET code as opposed to drag/drop data from the Server Explorer. You don't get IDE support for remote data.
Coding to a framework is coding to a framework. Assuming you include the right references, you can do anything the framework can do. This is true for C# Express or that other beloved developer tool, Visual Notepad.
[STOP: *pure* speculation and personal opinion - read my Disclaimer ]
If the Team System team were to release the Unit Testing Framework say on MSDN, then you would be able to create unit tests using Visual C# Express. That's a big "if", but if it happened, I think it would make a lot of people happy who can't necessarily afford VSTS but who want unit testing from Microsoft. You obviously wouldn't get tools support, but you could still write and run unit tests. You can of course always use any of the freely available unit testing Frameworks like nUnit and others.