Not to be rude, however where have you been for the better part of two years or so? Anyways, in answer to your question PCI-e is nothing more than an updated interface that video cards (mainly) use to physically connect to the motherboard. It offers way greater bandwidth than your familiar, although defunct, AGP 8X slot. SLI is what Nvidia calls its technology that allows two or more video cards to share the graphics load when rendering say...a game. Which for you is a good thing. ATI also uses the PCI-e slots and they too have a dual graphics card solution out there known as Crossfire. It does the same thing as SLI albeit in a different way. I havent any pictures, but with a tidy search of google images i am sure you can figure out what it is you are looking for. So in summary, PCI-e is the slots used that you stick the cards in. SLI is a technology that Nvidia uses to allow two or more graphics cards to share the rendering workload of a game essentially. Hope this helps....Cheers*