Is there a small portable version I can download without having to lose windows?
Yes, there is. Some distros have a LiveCD feature which allows you to test the operating system without making any changes to your PC.
Create a bootable USB with the ISO you choose and boot from it.
Another way is to download the VirtualBox and install then if you have Linux CD or ISO you can start installing it with VirtualBox but if you don't have any Linux OS you can download it from here
http://getintopc.com and you can dowload the VirtualBox from here
https://www.virtualbox.org/wiki/Downloads