what's inside the includes folder? I made a pretty dumb mistake..I was copying a library called ZendGdata to the includes folder within drupal and thought I copied all the files wrong so I deleted the folder and recopied the sub folder I wanted.  Right after, I got a white screen of death. 

I did a bit of research and realized the problem and restored the files from the orginal drupa install, but I'm wondering if there's any problem with it(the site works right now).  Is there any customized code or anything of that nature in the the /includes folder that will effect me later?
No, the /includes does not (if you haven't hacked core) contain anything personalized. That folder contains code that doesn't belong to a (core) module.

The correct place for libraries is sites/all/libraries, see http://drupal.org/project/libraries.