HD4870 core temps stock and modified

As of right now my computer is complete but I'm having a hard time deciding whether or not I want to put an Accelero S1 with a 120mm rigged onto it.

On one hand, a few friends of mine say that if I put the fan speed to 50% the difference would be a 5 to 10 degrees idle and 10 to 15 under load except that I wouldn't void the warranty.

On the other hand, my room is an oven as is and being in Texas it's usually 90 degree weather seven or eight months out of the year. I want to keep the PC as cool as possible but of course the warranty will be voided.

How hard would be to mod it back to stock should I decide to put the Accelero S1 on? If anything goes wrong I'm thinking about piecing it back together and taking it back to my workplace (I work at Fry's) to get a new one. Is there any type of adhesive used to keep the top plastic piece on the actual card and how different would the card look if pieced back together?

most card 'manufacturers' don't care if you change the heatsink. just don't break anything and your warranty should be intact.