First, find on the Apple Support site the right version of the Windows drivers for Boot Camp. For instance, this link takes you to the Windows XP 32-bit drivers update and this link takes you to the Vista/XP 64-bit drivers update. Keep in mind that you may need a different download for your particular Mac, just search in the Apple Support site. Store the drivers update in a drive you can get to in Windows (like an external USB drive or "thumb-drive").
Then, remember to back up your Mac. :)
Now, run the Boot Camp Assistant on your Mac. I don't believe you need access to the OS X installation disc to use the Boot Camp Assistant. You just run the assistant, set up your partitions, and then the assistant will prompt you to insert the Windows installation disc. After Windows set up is complete, you will have a very basic version of Windows without the latest drivers installed.
Now plug in the drive where you stored the drivers upload you previously obtained and run it. After setup is complete and the required reboot, you should see your Mac use the latest drivers.
Hope this helps.