As Tony says, there is probably a version name and license number for your operating system on a sticker on the underside of your laptop.
You can then use anyone's copy of the install disk for that operating system version so long as it's the right one, such as windows XP (professional) or Vista (Home Premium) to match your license.
There's an example of a disk on ebay if you can't get one from anyone else, it covers all Vista versions - I can't post the link but it's £15
Search for windows vista home premium or similar
It is obviously sold without a license
You may need a little technical knowledge when installing to get all your hardware working, depending on what's in it.
You should be able to get all the drivers you need if not from microsoft, then there's driverguide or similar websites, as well as the manufacturer's |