Topshelf is a .Net framework for C# and will need a .Net runtime to run on.
To work with Topshelf you will need to be running on a Windows operating system. The developers of Topshelf regulary test on Windows 7 and Windows Server 2008RC2. Though it should still work on Windows Server 2003, as long as .Net 3.5 sp1 is installed.
Currently Topshelf is tested on .NET 3.5 Service Pack 1 and .NET 4.0.