My wife uses a Dell Inspiron 1520.  It has the Intel Core 2 duo processor and 3 GB of Ram. She has been running Windows Vista since she got the Laptop about 18 months ago with no real issues.  Recently she has expressed an interest in Windows 7.  I offered to swap the hard drive for a new one (just in case she really wants to go back) and install the new Windows 7 64Bit RC1.  Some of my local IT Pros here in Salt Lake City have been bugging me about demonstrating how to do a USB based install of Windows 7 so I decided I would use the Inspiron as our demonstration example.  Before we begin there are a few things to keep in mind if we are going to be successful.   

1.  The system BIOS must support booting from USB.

2.  The USB Device must be of sufficient size to hold the installation files.  (In this case I want something 4GB or larger)

3. The USB device will have to be formatted with a file system including a boot sector.

4.  We will need the installation DVD to use as a source for the installation files.  

I went in to the BIOS setup for the Inspiron and changed the boot order and moved the USB drive to the top of the list.  (quick note to self. Go back and change the boot order after install.)

The drive I am using for this install is a Western Digital 120 GB USB drive.  That's way more size than we need, but it's what I had on hand so we will use it.    

Its important to get this next part right.  At first glance you might think you could just copy all the files on the DVD over to the USB drive and you would be good to go.  If you did you would find out very quickly that without a boot sector on the USB drive you aren't installing anything. 

I prepared the USB drive using the following steps after I plugged the Drive into a USB Port. 

1.  Right click on Command Prompt and choose "Run as Administrator"

2.At the prompt we are going to type "Diskpart"

3. We need to know the number of our USB Drive so we type "List Disk" The disks will be listed by number and by size.  Mine happens to be DISK1

4.  We select our disk by typing the command  "Select Disk 1"   

5.  Clean all files from the disk with "clean

This will remove all files from the disk. 

6.  To create a new partition we type "create partition primary"

7.  next we select the partition by typing "select partition 1"

8.  We mark it as the active partition by typing "active"

9. Finally we need to format the drive and create a file system.  We type "format fs=ntfs"

At this point I am really paying the price of using a big drive.  It took forever to format the drive.  That's all right because it gave me time to watch the latest episode of Bones on the FOX web site and a re-run episode of Survivorman on Netflix.

10. Finally we will complete the formatting by typing "assign" to give the drive a letter.  In our case the letter assigned was E:.  Type "exit" to close diskpart.

 

With the drive formatted we are ready to proceed to the step of making the USB drive bootable.

  1.  I put the Windows 7 RC1 install disk in the DVD drive.  (make a quick mental note of the drive letter of the DVD drive and the drive letter of the USB drive.)

2.  From the command prompt we change to the boot directory of the RC1 DVD  "cd D:\boot"

3.  We add the boot sector with the command "bootsect /nt60 e:" (where E:is the assigned letter of the USB drive)

4.  Lastly we copy all of the files from the Windows 7 RC1 DVD to the USB drive.

 

And with that we plug the USB drive into the Inspiron and we are good to go. The Inspiron recognizes the USB device as bootable and installation proceeds. 

I have to tell you that with this install I am particularly impressed.  All of the drivers were identified and seem to be running fine.  No issues out of the box is a great experience!

Well there's your step by step instructions for building a bootable USB installation for Windows 7 RC1.  Enjoy!   I will keep you posted as my wife tests this machine over the next few months.