Originally Posted by Aninimus

Yeah, I did. I tried Kalyway, iDeneb and iPC and only iPC worked (got to the installation screen okay).

I'll write a short guide to help you guys out.

Step 1:
Turn on the laptop, go into the BIOS and disable things that might be problematic (ie. 'Ethernet' and 'WiFi').

Step 2:
Download 'iPC 10.5.6' (I got mine from demonoid). Burn it using the lowest speed possible (X2 or X4, or whatever is the lowest option in your particular dvd burner)

Step 3:
Get an external USB DVD Reader, put your iPC dvd, boot into the USB DVD Reader.

Step 4:
Wait.. wait.. On the top, chose 'Disk Utility', Format your drive (remember to backup your data, formating will destroy everything). I formated using 'Mac OS Extended (Journaled)'.

Step 5:
Select the drive you just formated. Eventually you'll see a 'Customize' button, click it. Select the following:

Voodo Kernel 9.5
Video: GMA900
Chipset: LegacyAppleIntelPIIXATA
Ethernet: AppleBC5751Ethernet
Wireless: Intel 2200
Audio: AC97
Patches: PS/2 Mouse Fix, ACPI Fix, IOPCIFamily.kext patched, Seatbelt.kext 10.5.5

(IMO) For now: 'No more. No less.' I tried selecting different things various times and those above work, after you successfully install OSX and feel like trying to change the selection above and get some positive results (ie. you selected power management tools and they worked after the installation) please post here.

Step 6:
Continue the installation. Wait.. wait... Make your user/password/etc.

Step 7:
Turn off your computer, Re-enable Wifi/Ethernet/etc on the BIOS.

Boot into OSX (you can use the '-v' boot-flag to see what's happening at boot, errors/etc).

Congratulations! You successfully installed OSX Leopard on your dell x300!

What I tested and works:
- WiFi (No encryption, WEP, WPA-Personal)
- Touchpad (No scrolling tho..), Keyboard
- Native screen resolution (Video card works normally)
- USB
- Audio
- HDD related things (ie. Installing .dmg)
- Bluetooth (I could sync my phone and send/transfer files)

What does not work:
- Fn Keys (change brightness/volume/etc, you can change the volume manually by clicking on the 'speaker icon' on the top and you can change the brightness in the BIOS settings)
- Sleep (Please post if you get this to work!)
- Ethernet (I found a kext that makes this work, but breaks the sound. Post here if you want it, I'm too lazy to search for it now.)

Not tested:
Firewire
InfraRed

Good Luck guys/gals!