How to Install Windows 7 from USB Drive
I decided to reinstall Win7 on one of my laptops because it was acting up – turns out that’s not helping and I think at this point it’s a hardware problem (either memory or hard drive – I’m going to try memory next). In the course of troubleshooting the problem, I decided to rule out a bad installer DVD for Windows 7 (the installer was failing, saying it couldn’t access certain required files). So I created a USB installer for Windows 7 x64. And since I’ve been meaning to install Win7 on my Dell mini10 for a while (which has no CD/DVD reader), I also created a separate USB installer for it for Win7 32-bit x86.
I found this post to be helpful, but it has some problems in the original post that are corrected in the comments. However, there are about a million comments so to save you the trouble of reading them all and trying to figure out which are correct, let me just post what worked for me here. I’m sure this is not the only way to create a USB thumb / flash drive installer for Windows 7, but it is one that I can confirm works.
Requirements
You need a 4GB or larger USB drive.
You also need the 32-bit ISO for Windows 7 no matter what, and you need the 64-bit ISO if you’re planning on making a 64-bit installer. (I’m assuming you need the 32-bit ISO in order to run the bootsect command correctly from a 32-bit machine based on a comment I read. I haven’t tried creating an installer from a 64-bit machine nor have I tried running the 64-bit ISO’s bootsect command, so I can’t say how or if those methods work).
I performed all of these steps on a 32-bit Windows Vista installation.
Creating a Windows 7 USB Drive Installer
1. Download MBRWiz and unzip it to some folder.
2. 
Insert your USB drive, make sure there’s nothing on it you need (it’s about to all be destroyed), and Format it. If you’re in Vista you simply right-click on it and select Format, choosing NTFS as the file system.
3. Mount your Windows 7 32-bit ISO as a drive (using MagicDisc or something similar).
4. Open up a cmd windows with administrator privileges. The easiest way to do this is to go to Start > Run and type ‘cmd’ and then press ctrl-shift-enter (instead of just enter).
5. Change to the folder where you unzipped MBRWiz and run the following commands:
mbrwiz /list (note the disk number of your USB drive)
mbrwiz /disk=X /active=1 (replace X with the number of your USB drive)
In my screenshot below you can see that my disk number for my USB drive is 1, so I used /disk=1 /active=1 for my command.
6. Now in the same cmd window, change to your ISO mounted drive (in my case the F drive). Type the following commands, replacing e: with the actual drive letter of your USB drive:
cd boot
bootsect /nt60 e:
Your command window should read more-or-less like the following screenshot (click for full size):
7. Last, copy all of the files from your ISO mounted drive to your USB drive. If you are creating a 64-bit installer, unmount the 32-bit ISO first, then mount the 64-bit ISO and copy the files from there.
Summary
I just followed these steps, twice, to create one 32-bit and one 64-bit Windows 7 USB thumb drive installers. I can confirm that these steps work for me doing all of the creation work from a 32-bit Vista machine. I can’t attest to any other configuration or process’s likelihood to work or not, but feel free to comment if you have suggestions, improvements, or success stories to share.
Comments
Shaun Eutsey said on 14 Oct 2009 at 2:16 PM
Thanks, Steve, for all of the hard work. I don't need to install from a USB drive, but I know some people who have netbooks and this will be highly useful for them.
PHenry said on 14 Oct 2009 at 3:22 PM
I'm not sure if maybe I was lucky, but when I did this for my netbook, all I had to do was ensure the Win7 install files were at the root of my USB key and all worked like a charm (ie no need to "play" with boot records or other utils).
If you're doing this again, I would suggest taking a virgin USB Key, dropping your Win 7 files into the root and try that.
My netbook can only use USB Key for installs, no DVD.
Eric said on 14 Oct 2009 at 5:26 PM
I found Long Zheng's post also helpful with this: www.istartedsomething.com/.../tip-make-your-p
Eric said on 14 Oct 2009 at 5:26 PM
I found Long Zheng's post also helpful with this: www.istartedsomething.com/.../tip-make-your-p
Steve said on 12 Nov 2009 at 6:19 AM
I just can't get it to boot up. My MB supports booting from USB... I followed all the steps... I don't know what i'm missing!
John said on 24 Jan 2010 at 8:43 PM
Get NEW keys with this PRIVATE version ..just released
Get your copy doiop.com/.../win7keygen2010.
Jen said on 01 Mar 2010 at 3:43 AM
Works for 64bit as well.
Just change the mbrwiz to mbrwiz64
Great guide
Jen said on 01 Mar 2010 at 4:17 AM
Almost forgot to provide addtional Details
- The Win7 .iso file is from a 6.1.7600 version (64 bit)
- System would be Dell Studio 1555; 4GB RAM; ATI 4570 gfx
* Tip *
If yours is a dvd copy and want a bootable thumbdrive Installer (for obvious reasons)
I suggest creating a .iso file from the windows 7 dvd medium. This saves you time and possibly on the event of DVD scratches vs (Thumbdrive limited write amounts)
Win7er said on 03 Mar 2010 at 10:33 AM
@ Jen : correction to your post, the original wbrwiz will work on BOTH 32 and 64 bit windows 7 image
Scott said on 15 Mar 2010 at 6:24 PM
Is there a way to have a selection list for installing Win7 x32 or x64 from a 8gb USB drive?
Even More said on 23 Mar 2010 at 8:02 AM
Would be even more usefull to create a procedure and guide how to build just one usb media 8gb) containing both 32-bit and 64-bit installation medias - and some extra usefull software or drivers too. So not two separate usb-medias, but just one including both.
I think that it would need
- 32bit Windows 7 media installation on 8gb usb media as described
- creating 64bit-folder too in usb media root
- adding/modifying autorun-procedure somehow to as whether to run 32bit Win7 setup or that 64bit Win7 setup from the subfolder... So how to do that?
- creating extras-folder in usb media root and just to copy all drivers and extra software that you want into it - so just to be used from installed Windows 7 after Win7 installation
So how should intallation media's Win7-setup autorun structure be modified and what extra that usb media needs to enable first step selection of 32- or 64-bit Win7-installation?
Any suggestions?
Even More said on 23 Mar 2010 at 8:32 AM
Would that go by just deleting the autorun-file from root? So usb media just boots and then waits for you to run setup (32bit and to start Win7 32bit installation...) from the root or to browse in 64bit subfolder (where Win7 64bit installation media files are...) and then to run setup there (to start 64bit Win7 installation).
That would go by start setup.exe either in root or in 64bit subfolder (after cd 64bit).
Or could some kinda simple setup-selection command-file be created and modiry autorun to start it in usb media root? Something like
win7ver.bat
@echo off
cls
choice /N /C:12 Select Windows 7 version (1 32bit, 2 64bit)%1
IF ERRORLEVEL ==2 GOTO SECOND
IF ERRORLEVEL ==1 GOTO FIRST
goto end
:FIRST
REM Win7 32bit installation, usb root
start setup.exe
EXIT
:SECOND
REM Win7 64bit installation, usb 64subfolder
cd 64bit
start setup.exe
:end
EXIT
and to put win7ver.bat in autorun-file.
devaraj said on 11 Aug 2010 at 8:05 AM
Dear sir,
Thank you for your article, But i am unable to boot from my usb. when i was done all the things.
when i am going to boot from USB i am getting error like "Disk error" Please help my what is the problem. Thanks for advance