Well, she could always buy a Windows disc, and reinstall it herself. Honestly though, unless you know what you're doing, please don't do this. You need to go to a repair shop, they can probably reinstall Windows for you somewhat cheap. However, judging by your computer specs, I would seriously consider buying a new computer. Windows XP would probably run alright, but I really don't know if any shops offer XP installations anymore. With only 256MB of RAM, Vista and Windows 7 would run pretty slow.
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Never trust a man who, when left alone in a room with a tea cozy, doesn't try it on. -Billy Connolly