Checking for string contents? string Length Vs Empty String

Question

Which is more efficient for the compiler and the best practice for checking whether a string is blank?

1. Checking whether the length of the string == 0

Answer 1

String.IsNullOrEmpty() only works on .net 2.0 and above, for .net 1/1.1, I tend to use:

if (inputString == null || inputString == String.Empty)
{
    // String is null or empty, do something clever here. Or just expload.
}

I use String.Empty as opposed to "" because "" will create an object, whereas String.Empty wont - I know its something small and trivial, but id still rather not create objects when I dont need them! (Source)