How to install OS(xp/vista) from pendrive?

Windows OS can be installed from pen drive by making it bootable and copying the contents of the installer cd/dvd to the pen drive.But before that the pen drive should be converted just from a flash drive to a partitioned hard disk.It can be done through command prompt no software is needed.Here are the steps.........


1.At first the usb pen drive should be formatted in NTFS mode,in vista & 7 there is option to format pendrive in NTFS mode but in XP you have to follow some simple steps....
To format pendrive in NTFS mode in XP..................

• Just right click on My computer and click Manage and go to Device Manager tab or directly start--->Run---->type "compmgmt.msc" (without the quotes) then go to the device manager tab.....
• Double click on Disk drives and then right click on ur pen drive option.(Here my pen drive is showing as T.sonic650 usb device right click on that).
• Then click on properties.
• Then another window appears, in that window go to Policies tab.
• Under that tab choose the option "Optimize for performance" and click OK.
• Now u r done just go to my computer and right click on your pendrive and click format,u can find the NTFS mode for formatting there. 

2. Then go to start-->>;programs-->>;Accessories-->>;command prompt-->>;right click on that and choose Run as Administrator.

3.Then type the following.......

 Diskpart

 (It will open disk partition session.)

4.Then type list disk (shows the list of storage disks connected to your computer)

5.Now note down the disk no. of your pen drive,let it is DISK 1

6.Then type the following serially... and hit enter after every command...
     
          select DISK 1

    clean

    create partition primary

    select partition 1

    active

    format fs=ntfs

    assign

    exit

     

7.Now insert win vista/7 DVD to your DVD drive. Here i am assuming DVD drive as G and Pen drive as I.(Change it accordingly)

Now follow these instructions...

1. Type G:CD BOOT
2. Type this command BOOTSECT.EXE/NT60 I: to update your USB drive with bootmgr code.
3. Finally copy all the contents from the Windows Vista/7 DVD to your Pen drive. Make sure you don’t cause any errors.
4. Now set the boot priority to your pen drive from BIOS and you can proceed with the installation as normal.