XPS 600 nForce4 driver

I have the XPS600.  I went to nVidia website to download the lastest nForce4 driver, but there is a dilemma.  I see that there is nForce 4 Intel x16 and nForce 4 SLI Intel (without the x16).  Which one is the one that I'm supposed to download?

 

And what about the nForce4 SLI XE/Ultra Intel?  This is all so confusing.  Does all this have to do with what CPU you have?  I have the Pentium 4 3.2ghz HT.

 

 

Thanks a lot.