I have a Dell Inspiron 1720 LAPTOP with the Dreaded GMA 965 X3100. It's taken me literally MONTHS to get this together and working properly.
Today, after a long spell of reinstallationS, I got it working.
F*CKIN' A, YEAH.
SO- that said... I'll update here and on insanelymac.com and a few other places once I have more time- but now I jsut want to get the Sigmatel 9205 working with my vanilla kernel so that I can enjoy my HackBook Pro, which I paid a measly $200 for.
with that- i tried to sort out the files so that they made sense.  EE= /Extra/Extensions SLE=/System/Library/Extensions (duh)
So, in order to get this working...  YOU MUST FOLLOW THE DIRECTIONS BELOW IN THE ORDER THAT I HAVE PROVIDED THEM OR ELSE THIS WILL NOT WORK AND YOU WILL BE S.O.L..
Now, that we've got an understanding- do what you have to do to get 10.6.4 on your system. It doesn't matter- so long as it's running.
Once you've got that going, CAREFULLY do each of these steps in order.
1) Hold your breath for as long as you can. (just kidding... kinda.)
1) run the "Graphics Disabler" installation program. what it does is simply grabs ALL graphics related kexts and pushes them in to a folder at /S/L/E called "Disabled Graphics Kexts" (Personally, I moved the folder to my desktop, zipped it, and then deleted the original.)
2) CLEAR YOUR KEXT CACHE WITH SOMETHING LIKE OSX86 TOOL.
3) REBOOT your computer.
4) at the Chameleon boot, add the following flags:
-v -x VBIOS=Yes USBBusFix=Yes EthernetBuiltIn=Yes SMBIOSDefaults=No GraphicsEnabler=No
This forces your computer to boot in to safe mode, and with the VESA Graphics driver (default failsafe of sorts)

5) Add/Replace anything that you've got in /E/E with what I have added in my DL.
6) Add/replace anything that you've got on your system with what I've provided. VERSIONS ARE IMPORTANT, AND THE ONES I'VE PROVIDED ARE WORKING FOR ME AS I TYPE THIS OUT... (so if you don't remove something in place of what I've provided, then I won't be able to even begin to think about how to fix your issues.)
7) Use something like "Kext Utility to rebuild new Extensions.mkexts.
8) reboot, and cross your fingers and hope not to die.
9) at start, enter the following flags:
-v -f arch=i386 VBIOS=Yes GraphicsEnabler=No USBBusFix=Yes EthernetBuiltIn=Yes
(obviously, you can add these to com.apple.Boot.plist at your leisure)
10) you should be able to see that your graphics are defaulting to 1440x900x32... which, isn't the full 1680x1050x32 that it is capable of... but- well... it's better than 1024x768 ANY day of the week.
enjoy!