mentioning the licenses.

Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@2974

INSTALL

@@ -2,31 +2,44 @@ Things needed for compilation.
 
 SDL 
     The Simple DirectMedia Library available at http://www.libsdl.org
+    The dll distributed with the windows version of DOSBox is slightly
+    modified. You can find the changes in the sourcepackage of DOSBox
+    (src/platform/sdl-win32.diff). If you want the patched sourcetree
+    send us an email. (see README)
+    Licensed under LGPL
 
-Curses 
-    (optional)
+Curses (optional)
     If you want to enable the debugger you need a curses library.
     ncurses should be installed on just about every unix distro.
     For win32 get pdcurses at http://pdcurses.sourceforge.net
+    License: Open source
 
-Libpng
-    Needed for the screenshots. (optional)
-    For win32 get libpng from http://www.sourceforge.net/projects/gnuwin32
+Libpng (optional)
+    Needed for the screenshots.
+    For win32 get libpng from http://gnuwin32.sourceforge.net/packages.html
+    See http://www.libpng.org/pub/png/ for more details.
+    License: Open Source
 
-Zlib
-    Needed by libpng. (optional)
-    For win32 get libz (rename to zlib) from http://www.sourceforge.net/projects/gnuwin32
+Zlib (optional)
+    Needed by libpng.
+    For win32 get libz (rename to zlib) from http://gnuwin32.sourceforge.net/packages.html
+    See http://www.zlib.net for more details.
+    License: Open Source
 
-SDL_Net 
-    For modem/ipx support(optional). Get it from http://www.libsdl.org
+SDL_Net (optional)
+    For modem/ipx support. Get it from http://www.libsdl.org/projects/SDL_net/
+    Licensed under LGPL
 
 SDL_Sound 
     For compressed audio on diskimages. (optional)
     This is for cue/bin cdrom images with compressed (mp3/ogg) audio tracks.
+    Get it from http://icculus.org/SDL_sound
+    Licenced under LGPL
 
 ALSA_Headers
     (optional)
     for Alsa support under linux. Part of the linux kernel sources
+    Licensed under LGPL
 
 If you want compile from the CVS under a unix system, you'll also need 
 automake (>=1.6), autoconf(>=2.50). Should be available at http://www.gnu.org