Added gotchas section to README

README

@@ -54,6 +54,45 @@ Windows prerequisites
 - cx_Freeze, if you want to build a exe. You don't need it if you just want to run dupeGuru. (http://cx-freeze.sourceforge.net/)
 - Advanced Installer, if you want to build the installer file. (http://www.advancedinstaller.com/)
 
+Linux prerequisites
+-------------------
+
+- PyQt 4.7.5 (http://www.riverbankcomputing.co.uk/news)
+
+Prerequisite gotchas
+--------------------
+
+Correctly installing the prerequisites is tricky. Make sure you have at least the version number 
+required for each prerequisite.
+
+If you didn't use mercurial to download this source, you probably have an incomplete source folder!
+External projects (hscommon, qtlib, cocoalib) need to be at the root of the dupeGuru project folder.
+You'll have to download those separately. Or use mercurial, it's much easier.
+
+As far as I can tell, you don't *have* to compile/install everything manually and you can normally
+use `easy_install` to install python dependencies. However, be aware that compiling/installing
+manually from the repositories of each project is what I personally do, so if you hit a snag 
+somewhere, you might want to try the manual way.
+
+PyObjC's website is badly outdated. Also, as far as I can tell, the package installable with
+`easy_install` has good chances of not working. Your best bet is to download the latest tagged
+version from the repository and compile it from source.
+
+Also, on OS X, don't try to use the built-in python 2.x to install Sphinx on (the only pre-requisite
+that doesn't run on python 3 yet). There's some weird error popping up when dupeGuru tries to build 
+its help file. Install your own framework version of python 2.7, and then install Sphinx on that. 
+When Sphinx supports Python 3, things will be easier because you'll be able to install sphinx on the 
+same Python version you build dupeGuru with.
+
+Another one on OS X: I wouldn't use macports/fink/whatever. Whenever I tried using those, I always 
+ended up with problems.
+
+Also, I don't know yet if it's possible to compile dupeGuru with XCode 4, I haven't tried it yet.
+It's safer to use XCode 3.x. However, I don't see why it wouldn't work, so it very well might work.
+
+Whenever you have a problem, always double-check that you're running the correct python version. 
+You'll probably have to tweak your $PATH.
+
 Building dupeGuru
 =================