outdated, use the ATI Radeon HD Drivers
Tutorial from Griffsta
If anyone is looking for a great setup my rig is now complete and working perfectly! No TEARING! NO ARTIFACTS! Tested in OpenGL window apps and DVD Player etc. Fully Stable.
I finally got the patch working by just applying it myself using a hex editor. I am using the 10.4.4 version of the ATIRadeon9700.kext file. I have Sapphire Radeon X800 PCIe 256mb. This is non-pro edition.
This tutorial works for a Sapphire Radeon X1800 PCIe ( maybe for all X1000 series cards ) too.
Things that change if you have this card are:
Hex value to edit: 3D C0 71 00 00
Hardware ID in Info.plist: 0x71C01002
Note I am running the full resolution of my monitor via the com.apple.boot.plist option file. Device ID is 554F Vendor ID is 1002 of course.
1. Grab a HexEditor from http://www.macupdate.com/info.php/id/17562 2. Open the HEX editor and search for 3D 60 5B 00 00 in the kext file. This means the file at /System/Library/Extensions/ATIRadeon9700.kext/Contents/MacOS/ATIRadeon9700 (Note it should work on any version of the .kext 10.4.3-5 so don't fret if you don't have the 10.4.4 one!)
Be advised that this string occurs in two places. Once you find the two places that this string occurs, replace them with 3D YY XX 00 00 with XX being the first two digits of your Device ID and YY being the second. So for me it was as follows: 3D 60 5B 00 00 became 3D 4F 55 00 00.
3. Now go into the Info.plist file inside your ATIRadeon9700.kext folder and find the 0x5B601002 line and change it with your device ID like this: For example: 0x5B601002 became 0x554F1002 for my setup. Note that if your card has a different Vendor ID you need to change the 1002 to your Vendor ID as well!
4. Make sure your permissions are correct: chmod -R 755 /system/library/extensions
chown -R root:wheel /system/library/extensions
5. Now reload your kernel extensions cache kextcache -k /system/library/extensions
6. Now try a manual load of your driver before the reboot: kextload /system/library/extensions/ATIRadeon9700.kext
Reboot and pray to the gods!
7. Now if you were able to reboot and wish to change your resolution do the following! Goto /library/preferences/systemconfiguration/com.apple.boot.plist right before the closing line, add the following two lines to look similar to the other lines in the file <key>Graphics Mode</key> <string>WidthxHeightxColourDepth</string> So if my setup was 1280x1024 at 32bit colour, I would add: <string>1280x1024x32</string>
7. (Alternative) You can use a program called Callisto to change your resolution as well. 
Good luck and everyone keep up the hard work! If anyone wants to know my setup incase you need a 100% working rig. Here goes:
Pentium D 820 2.8Ghz Gigabyte I945P-Pro Motherboard Sapphire Radeon X800 PCIe 256mb 3Com 3C905B-TX NIC NEC ND-3540A DVD Burner And of course the onboard ICH7 Intel SATA
Hope this helps everyone; If anyone sees anything else that is incomplete let me know. Thanks!
Edited by Black Flame for clarity
Added X1800 data by /'hu:du:/ . . . . . . .