The Windows 7 beta has been released for quite a while now. If you want to follow the crowd and test it in your system, but do not want to burn into a DVD, here is how you can create a bootable USB drive to install Windows 7 on your system.
Step 1: Download Windows 7 BetaTo Download Windows 7 Beta Click
HERESave the file on your Desktop.
Step Two: Format a 4GB USB thumb drive
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My computer-->Removable disk(F)-->Right click and choose Format using the NTFS file system
Step Three: Extract the Windows 7 ISO file
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First Install
WinRAR 3.80Right click on ISO file and choose “Extract to ” as shown in the above picture.
Step Four: Copy BootSect.exe 
Open the extracted folder and open the “boot” folder, inside which we’ll find a file called “bootsect.exe” that we’ll need to use.Copy the file (CTRL-C) and then open up “Computer” or “My Computer” and double-click your C: drive.We’re going to paste (CTRL-V) that “bootsect.exe” file right into C: so we can easily access it in a moment.
Step Five: Make the Drive Bootable
Programs > Accessories and then right-click on Command Prompt and choose “Run as administrator.”
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Inside cmd, type and enter the followings:
- cd\
- bootsect /nt60 f:
We’re assuming the drive letter of your USB thumb drive is F:, so replace “f:” in the above phrase with whichever letter is assigned to your particular thumb drive. Hit enter and you should see:
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The thumb drive auto-load when you boot up your computer.
Step Six:Copy the Windows 7 files to the thumb drive
Now, copy all the files from the Windows 7 folder to the USB drive.
change the first boot device to your USB drive in the BIOS.
Reboot the computer.You should be able to install Windows 7 from your USB flash drive now.