Wiki.PKP.in

You could download Ubuntu Linux from the following link.
http://www.ubuntu.com/getubuntu/download

Its good if you could make your machine Dual boot.
For that you got to have enough space in your machine.

You may have problem in finding device drivers.

Windows applications can not run on linux by default.

Let me know if any question. Do it very carefully. Always have a backup plan.

Here is a picture how Ubuntu desktop looks like.

try linux mint

http://www.linuxmint.com

only 700 mb download. and better than ubuntu for laptop and wifi drivers are more likely to work better. since it is said to have mintwifi tool specific to linuxmint