You might want to read through some of the threads on the Ringtones, Themes, and Wallpapers
forum. I think this may help you solve your problem. It will take a little effort on your part thiough.
Search that forum for 7100i ringtones.
Hope this helps.
Edit: But please, if you do find a good, loud ringtone to use, turn it down when you're not in the noisy environment, especially the DC.