Hopefully you have your burners drivers installed. Some burners use your mb's or xp's default drivers, but for the ones that are supposed to use their own specific drivers, win xp drivers will make the process incredibly slow. If yours doesnt have its own drivers, you might want to up the speed, I once had a cd-rw drive that by default was on 2x, and it took like 3 hours to burn a full cd. Hope this helps.
(What software are you using to burn with)?