Use the patched kext I've uploaded. Can't you manually add the Ethernet interface in Network Preferences? How do you add the kext to the system? Is this a myHack installation?
Here:
AppleBCM5751Ethernet.kext.zip
If you right click on the kext, select Show Package Contents, then open in TextEdit the Info.plist file located in Contents subfolder, you'll see the PCI ids I've added for your card. That's basic kext patching
All Zero MAC address tended to be obtained with universal binary kext, hence why you should use the Intel version. Post us the output of Terminal command lspci -nn so that we can clearly identify your LAN card (needs lspcidrv.kext loaded), but HP documentation does indeed clearly state BCM5751 10/100/1000BT Ethernet...
Is it enabled in BIOS?
Look for the BCM kext of D430/D620/D820. Make sure to use the Intel binary version, not the universal binary PPC&x86 version. It's been mentioned in several threads (there's a detailed post about this re: D430 installation). You'll find the kext with a forum search on "universal binary" or on "BCM5751".
You need to post your full system specifications along with your zipped full /Extra folder, provided you've done a myHack installation with no other undocumented non-Vanilla modifications. Wireless cards are never an issue as it's a well known matter and is never supported through our bootpacks unless the card works OOB.
Ideally, you would also try other OS X versions from SL to ML.
All this has long been answered so please read up the forum and the various documentation pages. There is no need to confirm, re-confirm or re-re-confirm a process that has been explained many many times before.
I guess you did not read the BIOS info properly and you actually have the LoRes WXGA 1280x800 LCD. Update your BIOS to one of the latest versions (A16 to A18) if necessary and ensure BIOS setup is configured as per recommended parameters. If you follow the regular and documented process with myHack + OSXL bootpack, you cannot have black screen.
Once had a similar problem with a 2nd hand DW1490. Turned out the main antenna socket was no longer properly soldered to the card and one day I found the antenna cable in the air with the socket still attached to it. Card was basically goosed and went straight to the bin.
Check your BIOS setup and adjust if necessary as per recommended settings in dedicated pinned thread in this very section.
I take it you're using the bootpack that corresponds to your model, right? Because that black screen is a typical result of having no DSDT or the wrong one on a D630. If in doubts, double check your BIOS setup Information pages.
BIOS A11 should do, but I'd recommend you update to latest BIOS which is A16 if I'm not mistaken. You could also look at upgrading your CPU as you may find that this little T7250 is a bit weak performance wise...
Well, according to the log, you should have a DSDT.aml file in /Extra. Isn't it the case? There sure is one in the bootpack, so if EDP appears messed up, use the files from the bootpack.
Seeing the hardware is one thing... having it fully working can be quite another... Seeing hardware does not equate to support, absolutely not; take the example of the SD card reader on the D4x0: we all see the card reader in all versions of OS X, yet it's not supported.