if you really can't find a CD to restore it then have a look on the bottom of the laptop and see if there is a microsoft sticker on it with the windows license key. if there is then see if you can borrow a XP cd from somebody, it will need to be a XP pro, not home, CD though
If you can you can use that CD to install and type in your license key from the sticker and your still being legal.
However it would be a good idea to goto the fujitsu website and download all the drivers that you need beforehand and put them on a CD or usb stick.
get them here
http://www.fujitsu-siemens.co.uk/support/downl oads.html