Because it clones it. Down to the size even.
XP does not support booting from drives over 127GB in size so be sure not to exceed that in your boot drive size.
If you were mistaken about the OS, then correct that and ignore my warning.
-> XP and all current versions of Windows do not run from USB externals. It should blue screen and emit some driver problem message.
So many issues I see with this, all been discussed before.
I tried to clone my 80 gig hard drive to a 750 gig external hard drive with clonezilla. Disk wouldn't boot up and now it says it only has 91 gigs total space on it. I tried reformatting the disk and it still says it is only 91 gigs. How can I erase the formatting and expand the drive back to 750 gigs? Plus, I have started getting a blue screen a lot lately so I'm not sure if I need to just start from scratch with a clean install, although I don't want to have to reinstall all my programs and updates, that's why I want to clone. Any suggestions as to how to fix the problem and/or how to stop the blue screen? It says its a driver problem but I have updated all the drivers and still get the error. It is a fairly old Dell laptop (2006) with XP Media center and it's been a real trooper.