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Possible Duplicate:
Installing Windows XP from USB pen drive
How can I Install a fresh copy of Windows XP or windows 7 into USB flash

I'm thinking of changing to a new laptop that only comes with a 256gb SSD. It's not tons of room, but not inadequate either. One thing I have on my HD at the moment that takes up a lot of room but is rarely used is a partition with a bootable version of Windows 7 (I'm on a mac).

Would it be possible to install a bootable copy of Windows 7 onto a flash drive?

I was thinking of using a 64gb Sandisk Cruzer USB 2.0, so that when I need to dip into Windows every now and again I could just plug in the flash drive.

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marked as duplicate by Ƭᴇcʜιᴇ007, 8088, Simon Sheehan, ChrisF, Hennes Nov 17 '12 at 2:39

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

In fact you would need to dip into Windows dir nearly everytime, so you will have to have the USB stick plugged all the time. Windows files can be cached but I think you are trying to avoid this - because then it would make no sense to have Windows on USB stick. Back to the point - compared R/W time of USB stick to SSD disk - I don't see an option to do this - but that's not an answer - maybe it's possible. – laika Oct 25 '12 at 10:18
sorry i dont think i followed that, why would i need to dip into the windwos directory nearly evertime. Surely when i wanted to run windows i would just close my machine, plugin the drive and reboot using the usb drive ? both windows OS and content would be on the usb drive. In theory is that any different to running windows on a partion of a larger drive ? – sam Oct 25 '12 at 10:46
It sounds like a Virtual Machine would function better for you. This could be placed on a flash drive, much easier, then hacking Windows 7 itself on one. Only Windows 8 has a Windows ToGO feature which allows you to take a portable installation and actually boot from the drive itself on ANY machine. – Ramhound Oct 25 '12 at 11:29
@sam, skro is right in that, when running Windows, it will make heavy use of its boot drive, so even if you could do it, it would be slow and likely to cause pretty heavy wear on the USB stick. In fact, I don't believe it is possible to do at all for Win7, it can be done with WinXP. You can run a VM from USB but again, it's slow, expect startup times of several minutes. – Julian Knight Oct 25 '12 at 11:56
OK, I wasn't quite correct above, it can be done. See for Win7PE. There is also this… previous question. – Julian Knight Oct 25 '12 at 12:10

You haven't said how much space you need on your SSD?

Assuming that you are not too squeezed for space, I'd get rid of the Windows partition and install Oracle VirtualBox. Then create a Windows virtual machine. The virtual disk for this will expand itself as needed so it takes up the minimum amount of space. You also get the ability to run Windows without rebooting. The only real disadvantage is that Windows would not be quite as quick but really, as long as you have a reasonable amount of RAM on the host, you will not notice for most general use.

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the ssd is 256gb so once the OS and applications are on there i was expecting maybe 190gb left ? which is workable, but then to give another 50gb over to a windows partition, would begin to make things a bit of a tight squeeze – sam Oct 25 '12 at 13:16
@sam I think this is the most reasonable solution despite the fact the solution with Win7 Live USB is possible, unless you have an external SSD disk ideally with Thunderbolt interface. – laika Oct 25 '12 at 15:20
I'm not near my own Windows VMs at the moment so I can't tell you what size they are but they are not large if you don't have loads of applications and data on them. 10GB is probably enough? – Julian Knight Oct 25 '12 at 15:47

Provided your motherboard allows booting from flash disks, i think it should be possible although i have never tried it myself. Your flash disk would have to have an Master Boot Record which points to the location on the flash disk where Windows is installed.

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It can be done.
I would recommend to search for an online guide.
what you need to do is to format the USB, create primary partition and make that partition as active. then that partition can be used to boot from.
once it can be booted from, you can install windows 7/XP on it.
You can try to boot from CD and run windows 7 installation, when installation asks for path, choose the USB.
On this point, I am not sure he would allow you to do it, maybe the USB stick will not appear on the list of disks. so you need to bypass it.
anyway, for what you use it, It will be slow and uncomfortable to work from USB.

i done this with WinPE.

Please dont forget that Windows7 installation takes your disk (USB) and create 2 partition, one partition is 100MB and used for booting and another app, and the other partition is for the windows itself. you need to avoid this.

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