My replacement for the the VB Function IsNumeric... 

 public static Boolean IsNumeric(string stringToTest)

{
    int result;
    if (int.TryParse(stringToTest, out result))
    {
        return true;
    }
    else
    {
        return false;
    }
}
 
Or even better... (thanks Anon)
 
public static Boolean IsNumeric(string stringToTest)
{
    int result;
    return int.TryParse(stringToTest, out result);
}