Google "Ubuntu Windows dual boot" or sub in whatever distro you want. I'd suggest Arch. Ubuntu is bloated. Pm me I you want help with installing Arch. Arch can also be installed alongside Windows.
I would suggest giving ubuntu a spin before trying anything else.
Yes it might be bloated but it's the most user friendly distro out there and apt-get is one of the best package managers aswell. There are trillions of distros available and each serves a specific purpose. Ubuntu has taken up the task of bringing new users into linux and does pretty good at that.
Also keep in mind that many distributions provide live-cd versions meaning that you can run the operating system off a CD without touching anything on your hard-drive. That gives the advantage of "previewing" what you could be installing. Keep in mind though that the speed is SIGNIFICANTLY affected when running off a cd-rom (or a usb stick etc.) than running it off your Hard-drive. The last being the fastest ofcourse.
tips for getting a secondary hard drive or installing on an external drive.
I would suggest avoiding anything that connects to a usb port since from my experience the data transfer speeds are way too slow to make it worthwile. My number 1 choice would be a second internal hard-drive they're cheap and they're fast.
"I hope for nothing. I fear nothing. I am free." ~ Nikos Kazantzakis