Microsoft have created a framework called XNA specifically aimed at the Student / Hobbyist market. It is built on C# Express and is completely free. Initially for Windows, but it will create binaries for the XBox360. There is a US$99 fee to allow creating and debugging on XBox360 though. This is for membership to the "Creators Club".
I haven't read too much about it yet, but on the surface this looks really cool. Just wished I had a little more time to spend exploring this. I used to make 2D games in DOS using Borland C++, back in the days when VGA ModeX was pretty leading edge. Back then you wrote directly to the VGA memory. I suspect things have moved on a little since then.....