Ubuntu addict and loving it , the answerer ‘s intro attracted me.When I first read a book on linux ubuntu application, I was very moved, and feel tremendous love to it. I can recall the feeling which is not that strong to me at this moment. love easily fade. Nothing endures but change. Love is like fire, you need to add wood to it, to keep it on, or it will fade. There are definitely much disturbs, interferes every moment. When you love sth, just jump into it, do not wait till it fade ,especially ,you do not always have the chance to jump inot it. Now is alwasy the best time.
http://ubuntuforums.org/showthread.php?t=1743535
Only if you delete your existing Ubuntu partition.
You should make a backup copy of all your files and settings and store them all in some other media before you do any work on your computer‘s hard disk. Most people now have too much stuff to fit on DVDs, so either a USB flash memory stick or another hard drive will likely be needed, you can use a USB external hard drive if you want. I think that‘s what most people probably use these days.
If you want you should be able to resize your existing Ubuntu partition smaller to make room for your new Ubuntu installation and have two Ubuntus in the same hard disk. You can do that either with GParted in the Ubuntu CD or with the installer‘s partitioner during the installation process. Install a new Ubuntu beside your old one and then copy your files across. You still should make a files backup in another disk beforehand though, to be safe.
EDIT: Also, have you read this sticky: Graphics Resolution- Upgrade /Blank Screen after reboot ?