Emachines 520 Display Drivers - Screen Dimming

I am running a copy of windows 7 Ultimate, I have everything working great apart from one small thing; the dimming option for the display.
I know this is video card driver related, basically if I use the vista drivers specifically from the emachines website it works correctly, but the drivers are old (june 08) and game performance suffers. If I use the latest intel drivers (also the same one that windows update suggests) I get better performance (about a 10% increase in fps) but the dimming feature is no longer available.
I have also tried the intel generic vista drivers and the WDDM 1.1 drivers that come after the initial 7 install. Am I right in assuming that the computer manufacture has to customize the generic drivers from intel to allow the dimming feature? That is the only explanation I can come up with as to why the specific emachines drivers would work but nothing else. Is there a way to merge the two drivers, so I get the dimming feature from the vista driver but the performance from the W7 one?
Specs: Emachines 520, T3400 @2.16Ghz, 2GB Ram, Intel GL40 w/ 4500M, Windows 7 Ultimate RTM.

 

I fuss with few e525/e725 eMachines with T3000 cellys and T4300 pentium both dual cores based on GMA 4500MHD (GM45 tbe @475MHz by GPU-Z and not 533Mhz as it should be ) with installed Win7 b7600 Enterprise came out with dimming feature out of the box after installation. So it's probably something wrong either w/ installation of Ultimate or it's not final b7600, which build is yours? (or it has problems with smallest brother GL40 for some reason )

After install i still use default intel drivers for GMA4500 (win7 & wxp)to get little more options & to manage brightness & contrast for those LGPhilips LCD panels inside (LP156WH1-TLA3). Win XP SP2 of course didn't came with dimming feature out of the box cause they had no drivers for graphics.

I used this version 15.13.6.64.1908 [20090922] even if it says it's for Vista64 it works OK on Win7, while i see there's newer version now 15.15.6.64.1892 [20091009]

Hope it will help you.

 

Thanks for your input, I am running the latest build 7600 (or that is what winver claims)
I don't believe it is a problem with the installation (I have installed it twice from scratch and I still get identical behavior, and the same install works perfectly on my GF's Wind U100 with the dimming feature). I would try the drivers you suggested but they seem to be for x64 I'm running x86. I am pretty much convinced that it is a driver issue and not hardware, since I have it working correctly under one driver and just not the others. The weird thing is that it works fine with the vista driver from the emachines website, but if I use the intel driver from intel's website (be it the W7 or vista one) it stops working. This leads me to believe that either intel broke something in new driver releases or that emachines tweaked the intel driver. If someone could help me track down the 7.15.10.1502 vista x86 driver directly from intel I would be interested to see if that works since that is the version where it works directly from emachines.

Also it appears that the versions you linked to are the desktop versions, should I try those or was that a mistake?

OK so a little more of an update: testing several vista drivers (from various manufacturers) I have realized that any driver above 7.15.10.1591 causes a problem (1591 and below work fine). So the only thing I can assume is that intel changed something in the driver after that point.