Both are used and 20" but the 2.33 comes with the Nvidia 7600GT
Not if it's a 20" it doesn't. If it's a 20" it has the x1600. The 7600 was only an option on the 24" model.
That said, I'd still get the white one because it has a faster processor, more RAM, and a better graphics card (even the x1600 is better than the 2400).