Dual boot from external hard drive

[tashimee]

I am running a dual boot system with Ubuntu 12.04 and Win XP. My motherboard is dying. What I would like to do is turn my internal hard drives into external drives and plug them into my laptop until I can afford to buy a new motherboard.

Win XP is on an internal drive on my desktop, which I will turn into an external drive.

My question is: I have Ubuntu 12.04 on the internal hard drive on the laptop. Can I dual boot Ubuntu 12.04 with Win XP on an external hard drive? Since I am basically changing motherboards, is there anything that I have to do to windows, or Ubuntu?

[Geek-9pm]

Here is a short answer.
Ubuntu and many other Linux packages can boot from other devices and use GRUB is the thing to  manage the boot menu.
Windows XP was not built to run on an external drive. Still, some do it.
To learn more do a Google for:
How to Install XP on an External Hard Drive
You will find many articles.
Here is one:
https://www.techwalla.com/articles/how-to-install-xp-on-an-external-hard-drive

There is no simple way I know of. It is a lot of work.

Now what if you put XP on your laptop internal drive ? That is easy.

[camerongray]

Linux is generally happy doing this although the USB interface is generally fairly slow (especially USB 2.0) so you won't get the best performance doing this.  Windows on the other hand is not designed for running from a USB drive and moving a copy of Windows to a different machine will almost certainly cause it to fail to boot (and violates the EULA if it is an OEM licence and not a full retail one).

You are almost certainly better off backing up all data and installing the OSs properly on the laptop's internal drive.

[Geek-9pm]

camerongray,
Thanks. That is what I wanted to say. 
If he has enough memory, he can get Linux to put a lot of stuff into memory and it will run fast.
Here is a reference:
https://en.wikipedia.org/wiki/List_of_Linux_distributions_that_run_from_RAM

Worth mention...  Lighthouse Linux. This is an extension of Puppy Linux. It can run in RAM and is popular among the small Linux crowd. Once it boots up from USB, it perform,s well because it stays in RAM.

[Salmon Trout]

moving a copy of Windows to a different machine will almost certainly cause it to fail to boot (and violates the EULA if it is an OEM licence and not a full retail one).

As far as I know all Windows EULAs (OEM or retail) require installation on an internal drive.

[Geek-9pm]

As far as I know all Windows EULAs (OEM or retail) require installation on an internal drive.

I will not argue that point. The OP has choices he can make and he has been given partial help. I am finished here.