I decided to install Linux on my school laptop which has Windows XP installed on it. I want to be able to boot either Windows or Linux, so I don't want to overwrite XP. The hard drive is 40GB total and has about 20GB remaining. Could someone guide me through this? What software do I need (besides Ubuntu) to dual-boot? I know I need to setup a partition on which to install Ubuntu so will I need separate software to do this or does Ubuntu's install cover that? Is there a trusted website where I can find an Ubuntu torrent (newest version) other than the pirate bay? I don't trust it enough to download something that ends up being a virus.
Secondly, is there a way to backup an installed program on my machine in case something goes wrong? I have Microsoft Visual C++ which one of my teacher's friends installed on my class's laptops 3 years ago, and it wasn't done through the school, so I really can't risk losing the software. I don't know if I have a key for it (I have a Product ID in the About link but that may or may not be the serial #) so I can't just reinstall if something goes wrong.
After I do install Ubuntu, how's the setup? I guess I'll need to setup wireless internet again and that's basically it? What programs, if any, come pre-installed? How is the process of installing programs in general (is it double-click and go through a wizard like Windows or command line stuff)? What are some common commands I should learn? Anything else that I should know or any links to guides, tutorials or anything would be greatly appreciated too.