Good Gear Guide
Server walkthrough: inside the Dell PowerEdge T410...
Here is the PowerEdge T410 Tower Server with the shroud removed. You can see that it has an upside-down layout, with expansion cards are at the top and the power supply is at the bottom. This is a similar layout to Dell's desktop machines (such as the XPS 730x gaming PC).
Server walkthrough: inside the Dell PowerEdge T410 tower server