I successfully installed my D830 (nvidia 135M) with this process:
Started with this site: http://www.osxlatitude.com/edp/pre-installation/
Create boot USB pen: Followed Pre Installation steps, downloaded and executed MyHack (http://myhack.sojugarden.com/guide/) to create USB pen, but use the D630 (with nvidia) bootpack rather than the D830 (doesn't work), as advised here: https://osxlatitude.com/index.php?/topic/419-the-d830-osx86-sl-experiance/
Boot Dell with USB pen, follow instructions from Installation: http://www.osxlatitude.com/edp/installation/
Remove USB pen and reboot. Follow post-installation instructions but choose D830 as model for "Predefined Kexts". http://www.osxlatitude.com/edp/post-installation/
Everything including graphics, sounds, wireless, Ethernet, battery is working perfectly.
I then installed Windows 7 with the instructions found at http://www.osxlatitude.com/dual-boot-osx-windows-made-easy/ . Again everything went fine, laptop boots fine into Windows 7.
When I boot the laptop I get Chameleon loading, I hit enter to get the boot menu and I have two choices: OSX and Windows 7. While Windows 7 boots normally, OSX doesn't. The boot starts and a lot of kexts are loaded (so the right partition is found) but suddently I get a black screen and the computer reboots to Bios. Since this is very quick I can't even notice where the boot fails. Also, if I boot from my USB pen and pick OSX menu option then the computer boots the OSX partition without problem!
Any idea what this problem might be? Thank you.