I found  a workaround on  making usb flash drive bootable and make it able to install Windows 7 on a netbook without an internal or removal optical drive. Here’s how…

On a spare desktop/laptop computer  whether  it’s running on a Windows Vista or Windows 7 environment.

1. insert your usb flash drive (approx. 4-8 Gb. in capacity) on any available usb port.

2. Go to my computer and locate the usb disk – [example: Drive F:]

3. Point the mouse to the usb disk and right click “Format”

4. The File system: should be set to FAT (Default), Allocation unit size: default allocation size, Format options; check Quick Format don’t forget to click Start button.

5. Go back to my computer locate and make sure you inserted the Windows 7 installation optical disk, select all files and send to USB-DISK, (you can also copy and paste it) it takes several minutes for the copying of files to complete, when done, safely remove the usb disk.

6. On your new netbook set the bios settings bootup sequence to USB, restart, then insert the USB Disk.

7. Upon start-up sequence Windows 7  will start installing, follow on-screen instructions, setup procedures and you’re done.

Notes: Install necessary drivers, productivity and antivirus software when USB disk refuse to install use external/removable optical drive.