way to compare hard-drive's contents pre/post installs?

Quick question:
is there a way (be it app/terminal stuff) to compare the contents of my hard-drive before and after install an application ie: tell me what files have been added and where?

I ask because I'm about to reformat my computer which means all my big pro-apps have to be reinstalled and since I never actually know where all those bloody files end up I thought it'd be nice to have a listing of where each and everyone of these new files goes so when I do have to uninstall again (or move stuff to an external drive) i know exactly where to look.

thanks!

hrm

you could use diff to compare files generated by ls.

You'd have to do something like:

ls -lR / > filename1

then do the install then

ls -lR / > filename2

then diff filename1 filename2

It will show you all the differences. Would take a while, not sure if there's an easier way off the top of my head.