Yes it is possible assuming that you are doing it legally.
There are plenty of applications that do it for you like Toast.
Or you can use Disk Utility to create an Image of the disk then burn that to a dvd. That is the method that I have used since it's free
Edit: Here are the steps that I found off of a website called I'm not taking credit for this.
creativebits.org/
Making a DVD Image
Step 1. Insert the retail Mac OS X Install DVD into your drive.
Step 2. Launch Disk Utility (Applications > Utilities).
Step 3. In Disk Utility, you will notice a white pane on the left hand side. In the pane, select the Mac OS X Install DVD by clicking on it once.
Step 4. Click New Image on the Disk Utility toolbar.
Step 5. A dialog box will appear. Give the new image a name. I used 'Mac OS X Install DVD'. Select the destination where you wish to save it. Leave Image Format at Compressed (default) and Encryption at None (default).
Step 6. Click Save to begin creating the image.
Step 7. Once your image has been created DO NOT mount it. Leave the image alone and proceed to the next section.
Burning the Image
Step 1. Launch Disk Utility (Applications > Utilities).
Step 2. Click Burn on the Disk Utility toolbar (upper left).
Step 3. Navigate to where you saved the DVD image created in the previous section. Click on the image file, then click the Burn button. Do not drag and drop the image file into Disk Utility during this step.
Step5. Insert a DVD when prompted and proceed to Burn it. (use good quality media)
Using these exact steps I was successfully able to create a personal backup copy of Mac OS X Tiger. I hope this tutorial helps. Enjoy the newfound features in Tiger!