This might be be a little cleaner, and you can inject it as a dependancy (stolen from CodeCampServer):

public interface ICryptographer
{
	string CreateSalt();
	string ComputeHash(string valueToHash);
	string GetPasswordHash(string password, string salt);
}

public class Cryptographer : ICryptographer
{
	/// <summary>
	/// Create salt for encrypting user passwords.  
	/// Original Source: http://davidhayden.com/blog/dave/archive/2004/02/16/157.aspx
	/// </summary>
	/// <returns></returns>
	public string CreateSalt()
	{
		int size = 64;
		//Generate a cryptographic random number.
		var rng = new RNGCryptoServiceProvider();
		var buff = new byte[size];
		rng.GetBytes(buff);

		// Return a Base64 string representation of the random number.
		return Convert.ToBase64String(buff);
	}

	/// <summary>
	/// Create a password hash based on a password and salt.  
	/// Adapted from: http://davidhayden.com/blog/dave/archive/2004/02/16/157.aspx
	/// </summary>
	/// <returns></returns>
	public string ComputeHash(string valueToHash)
	{
		HashAlgorithm algorithm = SHA512.Create();
		byte[] hash = algorithm.ComputeHash(Encoding.UTF8.GetBytes(valueToHash));

		return Convert.ToBase64String(hash);
	}

	public string GetPasswordHash(string password, string salt)
	{
		return ComputeHash(password + salt);
	}
}