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How to switch back to Windows XP from Ubuntu without a DVD/CD drive? or what else can i do with the PC?

I have a Sony Vaio desktop PC, it originally ran Windows Xp but i later switched to Ubuntu. My DVD/CD drive no longer works, how can i switch back onto Windows Xp? or alternatively what else can i use this computer for.?

If you are able to put the hard disk into another machine you can use a boot CD to get into DOS, then insert a XP disk and go to the \i386 directory and run winnt which will start an installer that copies all the files needed to install XP onto the disk and then prompt for a reboot. When the system wants to reboot put the disk back into the Sony and boot it up, it will launch the normal XP setup from the hard disk. Or just swap a different CD drive into the machine.
have you still got the xp disk and a mem stick (about 1gb)

if so

you could use wintoflash http://wintoflash.com/home/en/