centOS installation

You need to wipe the drive with something like Boot & Nuke

http://www.dban.org/

Or Kill Disc

http://www.killdisk.com/downloadfree.htm

While both are free Boot & Nuke does a better job of destroying all Data on the HDD and Kill Disc is easier for some people to use. ;)

You need to know that you can not install any form of Linux onto a Windows Partition as Linux uses a different Partition Type that isn't compactable with Windows. It actually installs 3 partitions for the different functions of the OS so it can not work on a Windows Partition.

if you want to Dual Boot both Windows 7 and Cent OS you'll need to shrink the Windows Partition with some form of Partition Manager. If you don't have one you can use G Parted another free utility which is available here

http://gparted.sourceforge.net/download.php

To shrink the Windows Partition and use the free space to install Cent to.

If you want to mount Cent Virtually within Windows 7 you need a Version of 7 that Supports Vitalization so you'll need the Professional or Better version and then you can make use of the Virtalization capabilities of Windows 7. You'll however need Microsoft Virtual PC which is available here for the Higher Versions of 7.

http://www.microsoft.com/windows/virtual-pc/

Col

You need to wipe the HDD with something like DBan Boot & Nuke or Kill Disc both of which are free to download from their writers Web Sites.

You can then install Cent to the Blank HDD.

If you want to Dual Boot the OS you'll need a Partition Management Tool that allows you to shrink the existing Partition. If you don't already have one you can use GParted also available free from it's writers Web Site to resize/shrink the existing Windows 7 Partition and then install Cent to the Unused Space.

If you want to use Cent Virtually you'll need a version of 7 that supports Vitalization so that is Professional or above. If you don't already have Professional or above you can use the Upgrade Anytime option on the 7 Start Menu to upgrade to a version of 7 that supports Vitalization and then download Microsoft Virtual PC from the M$ Web Site.

Col