First, before someone else ends up saying it to you, you might want to take a gander at the
naming requirements page.
Anyway....
Funny
you should mention the MCTS exam.
I just passed 70-536 (.Net 2.0 Application Development) this afternoon, and am in the process of preparing for 70-528 (Web Client for .Net 2.0), so I might have a different perspective on this than a lot of folks here.
Personally, I think there's nothing wrong with being certified in multiple languages/technologies. (I'm learning C# because I got tasked with a project involving SharePoint and web parts. Joy of joys. We're otherwise a Java shop.) C# and Java are remarkably similar in many respects, though there are significant differences to factor in as well (interoperability with COM, reflection, code security, etc.), and I found the learning curve between the two to be reasonable in a short period of time.
Now, I don't know that MCTS is the greatest way to learn C# - if you go this route, make sure to do quite a bit of actual coding to reinforce what you're studying - but it's certainly one way to go about it...