Computer Troubles

I have had my Toshiba laptop for nearly four years. It has worked beautifully since the day I got it and I have credited that with being selective when downloading and installing stuff. Well today, it shocked me. I took it to work with me in order to do a presentation... the office provides laptops but I just love mine, so I always use it for work, school or fun. Five minutes before the presentation was to start, I booted up my laptop only to be greeted with a DOS looking screen that said a Windows file was corrupt or missing! I freaked out because I love my laptop; not to mention I had a room full of people waiting on me to start my presentation. Luckily, I had printed many of the webpages I planned on discussing because there was nothing I could do at work to fix the laptop. The meeting went over ok, but I was worried about my laptop for the rest of the day. Once home I found the Windows XP operating disk, inserted it and booted the system from CD/DVD drive. Voile'! It worked... the CD/DVD reinstalled/repaired the corrupt file and my laptop is back up and running. Now to back up the over 9GB of photos and 3GB of music I have stored on it just "in case".