Have you considered dual booting.
You can run more than one OS on the same machine!
As for Linux, there are Live CD editions, where you just boot up with the CD in the drive and it will happily run from RAM, just reboot with the CD removed and you are back to your original install, you will lose of course the Linux settings, but it will allow you to run it and learn without the full install/or find out if it will not work with your machine.
A good starter is Ubuntu, this has a reputation of picking up just about any machine setup. And can be run as a LiveCD and an install.
Mike is your man here.