If you want to change from WINDOWS OS to Linux, I recommend the Ubuntu to you. If you are using Ubuntu, I recommend the Xubuntu or Lubuntu to you. You can directly install Xubuntu originally, or you can turn ubuntu installed into Xubuntu.
Follow these steps for turning Ubuntu to Xubuntu in this web: https://sites.google.com/site/easylinuxtipsproject/alternative
You can also use the tips to speed up your ubuntu. https://sites.google.com/site/easylinuxtipsproject/speed
If you have any questions, please visit the web: http://askubuntu.com/questions