Want to try Linux? Don't have a CD/USB? Don't want to or can't partition? Use Wubi!
Requirements
Wubi
Enough time to download 800 MB.
Tutorial
1. Open Wubi
2. Select Hard Disk, doesn't matter you can install it to any with at least 3GB.
3. Select a installation size, this will act kind of like a virtual hard drive, you can change to a full installation later if you wish.
4. Select a Distro, Ubuntu is the best IMHO of the choices.
5. Select Language
6. Enter username and pass, Username must be lowercase, and you MUST have a pass in Wubi
7. Click Install.
8. Wait until it is done.
9. Restart Computer, A screen should show up asking you to choose an OS.
Congratulations, you now have Linux.
NOTE: IF you screw something up, it is not my problem.
To install Java use this command: sudo apt-get install sun-java6-jre sun-java6-plugin sun-java6-fonts
I had issues downloading java from the site, so that could help.