When i erased my hard drive what system of Windows do i need to put on it

How to Format a Computer with Windows 7 Warning - Formatting hard drive information does not permanently erase the data. Even after a computer has been formatted, deleted files can be easily recovered. If you want to permanently wipe your hard drive by completely overwritting hard drive data, check out various programs that will ZERO out the drive.
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To format your hard disk during Windows 7 installation, you'll need to start, or boot, your computer using the Windows 7 installation disc or USB flash drive.

1. Turn on your computer so that Windows starts normally, insert the Windows 7 installation disc or USB flash drive, and then shut down your computer.
2. Restart your computer.
3. Press any key when prompted, and then follow the instructions that appear.
4. On the Install Windows page, enter your language and other preferences, and then click Next.
5. If the Install Windows page doesn't appear, and you're not asked to press any key, you might need to change some system settings. To learn how to do this, see Start your computer from a Windows 7 installation disc or USB flash drive.

On the Please read the license terms page, if you accept the license terms, click I accept the license terms, and then click Next.
On the Which type of installation do you want? page, click Custom.
On the Where do you want to install Windows? page, click Drive options (advanced).
Click the partition that you want to format and click Format.
If you have more than one partition on this hard drive and want to get rid them to make one big drive again, then select a partition and click on the Delete option for each partition. Once you have deleted all of the partitions, select the Unallocated Space partition and click Format.
Pick the formatting option that you want.
When you've finished formatting, click Next.
Follow the instructions to finish installing Windows 7, which include naming your computer and setting up an initial user account.
If you do not want to reinstall Windows 7, you can cancel the installation at this point and keep your newly formatted drives.

This information has provided by, youc an also find instructions for other operating systems here: How to Format Computer

Yes, I had the same ...
To put things right I downloaded Linux Ubuntu (http://www.ubuntu.com/download), burnt it to dvd and used the non-working hard drive as the only master drive, and installed Ubuntu as the operating system. Then I erased Ubuntu by installing Windows XP.

As you already have Windows working on your computer, why not create a 'virtualbox' and install the tech preview inside your current operating system? Search for for Oracle virtual box for Windows hosts (http://www.oracle.com/technetwork/server-storage/virtualbox/downloads/index.html), download it and also download the guest box additions.

That just means if you have say, Windows 7 as your operating system, you create a virtualbox and install another operating system inside that virtualbox. You can run both operating systems at the same time.

If you don't fancy the idea of a virtualbox, you can use the inbuilt Windows disk partitioner to create another drive on your hard drive and install the tech preview there. Your computer will be 'dual boot' ... at start up you choose which operating system to use.

You can do the same using Linux - but be aware that Linux must go on as the SECOND operating system.

Your first port of call is to format those hard drives and put things right.

Once you start installing Windows 7 from your disc, you will be able to erase Ubuntu simultaneously. To know how it works, you can refer to the following link:
http://www.wikihow.com/Erase-Ubuntu

The following link can be helpful while installing Windows 7:
http://windows.microsoft.com/en-us/windows/installing-reinstalling-windows#1TC=windows-7

GuruAid.com

If you have a Windows 7 installation disk, just put the disk in your drive and follow the instructions......it will remove your XP and install a fresh Windows 7

Hello, it looks like somehow the master boot record was erased from the hard drive, maybe viral? You mentioned the hard drive was recognized in the bios correct? If you need data from the hard drive the easiest way would be to pull the hard drive out and use an external hard drive enclosure to remove the data before you erase everything from the hard drive. If you dont need anything thing you can proceed to do a new install of Windows 7. Turn the computer on then hold alt and the f10 key to perform a factory recovery. This will erase everything and reinstall Windows 7. If this doesnt work then you will need a new hard drive and a bootable usb drive with Windows 7 on it. Hope this helps.

I think your problem is this, you try to install Windows XP with a pre-installed Windows 7---windows doesn't accept downgrading of O.S., so the best solution on this would be to erase Windows 7 or format the hard drive and install a fresh Windows XP.

Are you installing within Windows? If so reboot your system with the Windows 7 system disc inside your cd rom, you should see message that says Press Any Key To Boot From CD at this point press any key. The system will load the installation files the it will ask you if you want to install or perform recovery you will select install, then it will ask you if you want to format your hard drive. Formatting your hard drive will erase the entire drive so back up any desired files. This will successfully install windows 7.

It only erases it if you tell it to, and it would only be the C: drive in any case.

Fastest, and most efficient way to erase an hard drive is by formatting it.

If the hard drive is the one in which the system is installed, then you will need to boot the computer using the system install disk (eg. Windows XP disk) to format the hard drive.