There is absolutely no compelling reason to choose SharpDevelop over Visual Studio if you have the choice and the budget.
Visual Studio is by far the best IDE on the market, and I have used quite a few.
And, as Marty says in comments, he is a student. At http://www.dreamspark.com any student can get free, full professional versions of most all of the Visual Studio and Windows SKU's.
Visual Studio is also offered without cost in less featured versions labeled 'Express'
If you are not a student (or don't know one, wink wink) and on a budget, and the VS express versions don't have the features you need, then SharpDevelop would be a good way to go.
I am not an MS fanboy, just in case you are wondering.