Insert your OS disc. Change the boot order to boot off the optical drive first. Then restart. It will prompt you to 'press any key'. Select the appropriate partition. Then choose the 'r' option to repair your current windows install.
When you get to the command prompt, use the fixboot command to repair the boot files.
^ this will not cause any data loss. The fixboot command will simply overwrite current boot files. If the second option is necessary, it's simply extracting a file off the OS disc.
What version of windows do you currently have? Windows7 does have an xp environment but it is pretty resource hungry. I doubt your laptop will have the sufficient resources to run it. I believe they recommend 3G of memory, but you may be able to run it with 2Gb.
There are websites where you can download the file. However, I'd be REAL cautious about that. I would download it to a blank flash drive or floppy or something other than a HD, and scan it thoroughly. If you get a clean one, then you can paste it in your system32 folder.
If you can get into safe mode w/ f8, then we can work with that.
However, if you did download the file, you could extract it off the disc and put it in the system32 folder, much like the 2nd solution I linked to above.
You will also need to make a bootable floppy disc to boot the pc to a command prompt. The command prompt is where you will tell the pc to take the file from the disc and put it in the system32 folder. In xp the OS disc is bootable, so the floppy boot disc isn't necessary. But since you don't have an OS disc, this is the only workaround. http://www.computerhope.com/boot.htm