Wubi is Simple
No need to burn a CD. Just run the installer, enter a password for the new account, and click "Install", go grab a coffee, and when you are back, Ubuntu will be ready for you.
Wubi is Safe
You keep Windows as it is, Wubi only adds an extra option to boot into Ubuntu. Wubi does not require you to modify the partitions of your PC, or to use a different bootloader, and does not install special drivers. It works just like any other application. Wubi is free of spyware and malware, and being open source, anyone can verify that.
Wubi is Discrete
Wubi keeps most of the files in one folder, and if you do not like it, you can simply uninstall it as any other application.
Wubi is Free
Wubi and Ubuntu cost absolutely nothing (free as in beer), but yet provide a state of the art, fully functional, operating system that does not require any activation and does not impose any restriction on its use (free as in freedom).
Download wubi for ubuntu 10.04 from here