The best part - Live CD

The best part about Ubuntu is that you can use a live CD to check it out.

• What's a live CD?: Well, it lets you run the OS without actually installing it. All data is stored on RAM and so any changes made in the OS will be temporary. The OS will run slower than when installed due to CD speed constraints.
• How to create a Ubuntu live CD: Download the Ubuntu OS ISO image and burn it using any CD writer software.
• Running from the Live CD: Make sure you have set "Boot from CD" under BIOS and off you go.
• Pros:
• Lets you determine if the OS is really meant for you without actually installing it.
• Comes in handy when you have a system crash - You can recover all files.
• You can determine if the OS runs smoothly on your PC.
• Don't like the OS? No hassle uninstalling it. Just shutdown and remove the CD.
• Cons:
• The actual execution speed of the OS can't be determined.
• Once the image is burnt, the CD can't be used for other purposes unless it a RW CD
• Alternatives to burning a CD:
• Install a virtual machine, mount the ISO image and run the OS.
• Create a Bootable USB drive and run the OS.

Note: You can use a DVD instead of a CD.