The case the OP references is a nice case for the average pc user, but may fall short for extended gaming sessions with a hot running gpu. It's all about case ventilation, which systemlord points out, or more specifically, case volume air exchange or throughput. The referenced case appears to have just an 80mm on the side panel and unfortunately the hard drive cage mounts sideways, which allows easy hard drive access but restricts the air flow from from any input fan you might want to install. The "open throat" hard drive cages that are aligned with lower input fans are the better design, IMHO. If the side panel had a CAG tube over the cpu and an input fan pulling air down over the cpu hsf, you would in all likelihood see appreciably lower cpu temps.
I have two E6600 boxes with 8800GTXs in each, and run 32-34 °C at idle and no more than 44-48 °C under heavy gaming load at an ambient temperature of around 75 °F. One case, an Antec 640B, has two side panel fans, one a 92mm at the end of a CAG which blows straight down onto the cpu/hsf, an 80mm blowing directly below the GPU, a 120mm exhaust at the rear of the case, and a 80mm in front of the hard drive bay. The other is an old Sonata 1, with a 120mm modded to the side panel blowing directly on the gpu and north and south bridges, a 120mm on the inside surface of the the fan cage blowing directly onto the gpu, a 120mm at the rear of the box, and an Antec Spot Cool mounted to the mb and blowing directly down over the cpu HSF. Both boxes have Corsair HX520s which for me, helped to lower the interior temps because they just run a lot cooler than my old Antec NeoPower 2s. Before, and running two unmodded Sonata 1s, my idle temps for the E6600 were right at 52 °C, peaking to 65-70 °C under heavy load - just too hot!
As I see it, you have two options. One is to keep the existing case and add some modifications. Since you have a plexiglass side panel, you could mod the side panel to mount a larger fan, and mount a "Spot Cool" over the cpu/hsf to try to bring the temps down lower. Adding a 120mm fan in front of the hard drive bay would help a little also, in spite of the 90 ° orientation of the drive cage. You could also exchange the PSU for a robust "name brand" one having a good active PFC rating, which would run cooler in the case therein contributing less to the heat problem.
The other option is to buy a new case, one that will give you the kind of heat exchange that allows you to run all componenets at lower temps and therein increase the lifetime of all your components. The Antec 900 would really cool your system down.
Just my 2 cents...and good luck!