I want to install Ubuntu 12.04 on my Laptop. How much I need for root, home and swap partition? I have 3GB RAM. I will use Ubuntu for installing any kind of interesting packages and doing some programming. And, another question, can I use any partition (which is being used by Windows 7) as my home folder in Ubuntu?
Note that you don’t need to put root and home on separate partitions, and the size depends on how much data you will store on your home as well as total space available on your hard disk. For example I myself prefer storing data on Ubuntu because on journaling file types (ex2, ex3, ex4) my data won’t get fragmented or even virus-infected and it’ll be faster to access them.
So let us know, if possible, how much space you have and where you will store your data more: Windows or Ubuntu.
For swap, you can visit this SwapFAQ; if you have much space, 3 GiB is highly recommended.