Well, if you want to overwrite Ubuntu, then you don't need any of them.  Also, keep in mind that Windows cannot use ext4-formatted partitions, so if there is data on that partition that you need, back it up now.  When you install Windows 7, simply delete and format all partitions on the disk. 1.  The Dell Utility partition contains diagnostics that can be run during startup, but you don't need this, as you can download the same (actually newer, updated) diagnostics from support.dell.com to run instead.  Delete it. 2.  This is your partition that Ubuntu is running on ... if you are overwriting Ubuntu, then this must go.  Delete it. 3.  This is your data partition for Ubuntu ... as it is formatted in a format recognized only by Linux, it is useless to Windows.  Delete it. 4.  This is your swap partition (used like a page file in Windows) ... used for Ubuntu and useless to Windows.  Delete it.
Yesterday, I have bought Vostro 3500. Ubuntu 10.10 is already installed on it.   Now, I want to install Windows 7(32 bit), by overwriting the Ubuntu OS. When I was trying to install Windows 7, I found that there were 4 partitions on my Hard disk. Please, let me know what are the partitions that I should not delete. And also provide me some good reason.   Thank you. [IMAGE]
How to Install Windows 7 on a brand new Vostro 3500, which has already got 
Ubuntu 10.10 on it.