Apple iMac Graphic FW Update2.0

Go to the Appple on the menu bar, About This Mac, click on More in the open window, choose Graphics/Displays. If you have either ATI Radeon HD 2600 Pro or HD 2400 XT *and* if you have a 20 or 24-inch aluminum iMac, then you may need to install this update. That said, I wonder if this is Apple's 'get out of jail free' card for all of us who have complained that our iMacs suddenly and randomly shut off for no apparent reason. I ended up taking mine in for an Applecare repair for that exact reason, and ended up getting a new LCD because of what I had assumed was smoke residue on the inside of the glass.

Hmm...what do ya know,yet another imac firmware graphics update that apparently my 24 inch imac doesnt need!!! so friggin stupid,i have had my imac for 2 years now and i think this is the 3rd or 4th firmware or graphics error update,but havent been able to apply any since the installer continually tells me i do not need this update! i sent the update to my brother who has a brand new 27 inch imac,and it also told him he does not need the update! TOTALLY USELESS!!!!

Which iMac is this update good for?