It's possible to connect a normal PC DVD-drive to your xbox.
This is very usefull if your xbox has a bad laser. A pc DVD-drive will not only give better results for DVD-r/rw , but also for CD-r/rw.
A pc DVD-drive will play pretty much all brands and load times will be shorter then when using the official Xbox DVD-drive.

What you need ?

A pc DVD-drive
A normal PC powersplitter (4 Pin Power Connector for 5.25 Drive , like used in normal PCs)
An original xbox game (depends on dvddrive)
A modded xbox console

The Installation

Put your PC DVD-drive in slave-mode.
Open the top of your xbox.
Leave the Xbox DVD-drive in its slot. (you can NOT just replace the drive , in order to make this work you will need both drives).
Put the PC DVD-drive on top of the Xbox DVD-drive.
Disconnect the IDE cable on the Xbox DVD-drive and connect it to the PC DVD-drive.
Leave the 8wire yellow cable on the Xbox DVD-drive.
Disconnect the Xbox HDD Powercable and connect the power-splitter on it. Now connect one end of the splitter back to the Xbox HDD and the other end to the PC DVD-drive.

Your xbox is now ready to read CD-RW/R and DVD-R/RW from the PC DVD-drive.

How to boot games ?
The are 2 method to boot games with a pc-dvddrive. I can't say which one will work with your drive , so just try them both.

METHOD1
Insert nothing in the xbox-drive.
Open the PC drive and insert disc.
Close the PC drive.
Reset Xbox. (reset button or "reboot xbox" in EvoX).
Game should launch , if not , try METHOD2.
 

METHOD2
Eject the xbox drive (<-- Xbox drive!!)
Insert the CD-r/rw or DVD-r/rw disc in the PC drive (<-- PC drive !!)
Close the xbox drive with an original xbox game inside. (<-- Xbox drive!!)

For DVDmovies you can do exactly the same.

NOTE:
1/ You can NOT play original discs this way , you will have to reconnect the IDE-cable to the Xbox DVD-drive if you want to play an original games.
2/ You will have to keep your xbox open. Make sure you protect it from dust.
3/ It's unsure if this tricks works with ALL PC DVD-drives.