I'm glad you asked that question. The see-through windows on each side are kind of like a bubble. They extend out several inches and counting the extra inch from the mounts the motherboard is placed on, now you have the heat from the cpu about 3-4 inches from the actual plastic. Running an AMD TBird 1.4 gig cpu using a simple $10 Volcano 5 as the heatsink/fan combo heat was never a problem. Nope, nothing melted or even gave any hint of it. After hours of using graphic intensive applications and playing games you couldn't feel any heat at all on the outside of the case where the cpu was nearest. Highest the temp went to was 114 degrees. And for a TBird that is excellent.

Notice in the picture above how the Millenium Case has that "custom window" that many want built-in and pay extra for. That's the side the motherboard is on and if you use all round cables then things will look cleaner and more neat. Also notice you have space to run cables under the motherboard. But doing that doesn't add to the outside looks obviously. And hey! You can lock it up to help keep things safer. Below you see how the other side looks and a better view of where the power supply is.