It depends on how you got it. If it came through Windows Update then it will be tailored to your particular laptop and once in will show in updates, you will need to show all updates by the way. As far as I am aware you cannot retrieve it for copying.
If you downloaded it from the Microsoft download centre click here then you should be able to re download it ( if you cannot find it in your normal download file) save it and burn it. but be warned it a big file.
Hi, Anskyber, Have downloaded the file 445Mb! Took 12mins on a BT Broadband. Why do you want to do so? I have a new laptop, no software, other than the recommended backup disc. The full download can be used as a re-install of Vista, without having to worry about keycodes. At least that's what I understand from other threads.