What you need is:
if (!File.Exists(@"c:\test\Test\SomeFile.txt")) {
File.Move(@"c:\test\SomeFile.txt", @"c:\test\Test\SomeFile.txt");
}
or
if (File.Exists(@"c:\test\Test\SomeFile.txt")) {
File.Delete(@"c:\test\Test\SomeFile.txt");
}
File.Move(@"c:\test\SomeFile.txt", @"c:\test\Test\SomeFile.txt");
This will either:
Edit: I should clarify my answer, even though it's the most upvoted!
The second parameter of File.Move should be the destination file - not a folder. You are specifying the second parameter as the destination folder, not the destination filename - which is what File.Move requires.
So, your second parameter should be c:\test\Test\SomeFile.txt.