Installing Windows 7 can be done in a multitude of ways. There’s the normal installing from a DVD approach, installing directly from the hard drive, and even installing via a network, among many other methods. My favorite, however, is installing Windows 7 directly from a USB drive. This allows a couple of benefits. First, it’s a great way to have a very portable method of installing Windows 7 on the fly. It’s also a little bit faster than installing directly from a DVD. And there’s also the convenience factor for those who use netbooks or others mobile devices that don’t have a DVD drive installed.

You will need at least a 4GB USB Key in order to create a bootable Windows 7 install. However, as this process can be used for a variety of OSes, your mileage may vary. For example, XP or Ubuntu only need about 1GB of free space, thus a minimum of a 1GB USB disk is required.

Setting Up the USB Key

First we’ll have to start DiskPart, a tool that comes standard with Windows that can be used to partition disks, create new volumes, and much more. If for some reason, you don’t have DISKPART installed, feel free to download it from Microsoft.

To get DiskPart up and running, open up your Start Menu and type diskpart and then press <ENTER>. If you have Windows XP, select the Run command from the Start Menu and type diskpart instead. The DiskPart utility will start up in a Command Prompt window and should look like the following:

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From here, we’ll have to enter in a few commands, nothing too tricky and as this will be a step by step process, you should have no problems. If you happen to make a mistake, however, simply start over from the beginning. The entire process takes only a few minutes to complete, so you won’t lose a whole lot by starting over.

Type in the command LIST DISK. This will bring up a list of disks currently installed and running on your PC (note, however, it will not show networked drives). The disks will be ordered by their Disk #’s, a completely arbitrary numbering system that isn’t specific to each disk per se, instead is incremented by the order that they are installed, with Disk 0 being your main hard drive. Note which disk number your USB key is for the next command.

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Here we can type in SELECT DISK N, where the letter N can be replaced by the number that corresponds with your USB key. For example, my USB key resides in the position of Disk 2, thus I would type SELECT DISK 2. Using the SELECT DISK command ensures that we have selected the correct disk and are not about to change the information on any of our other disks. By default, DiskPart will select Disk 0 (your main hard drive) if you do not manually select a disk to modify.

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Next, we need to wipe data from the disk and prepare it for the next steps. This will erase all the data on your USB key, so make sure to back up the data before continuing on. Simply run the CLEAN command to do this.

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Now we get to make the disk into a primary partition, thus enabling it to be read like a normal hard drive and enabling it to load files from while starting the PC. Run CREATE PARTITION PRIMARY to enable the disk as a primary partition.

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Now, type ACTIVE to make the current USB key the active partition.

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We’ll need to convert the disk to the FAT32 file system if it hasn’t already been done. You’re disk may already be formatted with the FAT32 file system, but for completeness sake, we can simply change it anyway. Simply run the command FORMAT FS=FAT32 QUICK. The QUICK appendage ensures that we are doing a quick format which will take only a couple minutes at most to format the hard drive. This won’t remove data on the disk per se, but will instead remove the indexes Windows uses to locate the data, thus making it look like there is no data left on the USB key. (On the other hand, by not using the QUICK appendage, Windows would try to delete all of the data on the key, although useful in some cases, this is completely unnecessary to do and a waste of time.)

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Now we need to assign the USB key a drive letter. Type in ASSIGN to do so. The USB key will be given a drive letter that follows immediately the highest predecessor drive’s letter (i.e., if you currently have C, D, and E, the USB key will receive drive letter F).

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To close out of the DiskPart utility, type EXIT.

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Getting the Files onto the USB Key

We’ll need to copy the Windows 7 setup files over to the USB key. This can be done via two processes, either from a Windows 7 DVD, or from a Windows 7 ISO file that may be lying around on an external hard drive somewhere.

If you’re going the DVD route, simply insert the DVD into your hard drive, browse the DVD with Explorer and copy over the entire contents of the DVD over to the USB key.

Getting the install files from an ISO file is a little bit trickier, but still possible. The trickiest part is to open up the ISO file, once you have the correct tools to do this, the problem should be a snap, however. I suggest grabbing a copy of 7-Zip or IZArc will allow you to easily open up an ISO file and copy the files over to the USB key.

Installing Windows 7 From the USB Key

Now for the fun part, actually installing Windows 7. The install should go about exactly the same way as if you were installing directly from the hard drive (another article for another time!) or directly from the DVD.

Some users may need to enable booting from a USB drive from the BIOS. The BIOS can be opened when you first boot up your PC by either pushing the F1 or F2 key (is varies on different models, but these are the two main keys to push). The option is usually found somewhere under Boot Options.

Once you’ve made sure that your PC can boot from a USB drive, plug in the drive to your USB port, turn on or restart your PC and you’ll be able to start the install process.

Wrapping It Up

You now have a bootable Windows 7 installation USB key. No need to worry about having to lug around DVDs or having to hook up an external DVD drive to your netbook or other ultraportable machine. This can also be very useful for back up purposes, or when needing a recovery disc to restore files on your PC.