If the hard disk is blank then there's little you can do to install Windows without a Windows CD.
However assuming the hard drive is still usable, have you thought about Linux? It is a free, open source Operating System, and can be downloaded, burned to a CD, and installed from that.
There are many flavors of Linux, called Distros. One I have heard of but never tried is Ubuntu.
More information about Linux here; http://linux.co.uk/
Mark
I got my wife's old laptop out of the shed and want to bring it back to life. When I start it up it asks me to install the Windows XP CD which I don't have. What can I do? I don't want to spend money and can't afford another laptop - I have nothing to lose by messing around with this one.

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