diff --git a/modules/module-list.nix b/modules/module-list.nix
index 537e6181469..f0a17bcd870 100644
--- a/modules/module-list.nix
+++ b/modules/module-list.nix
@@ -117,10 +117,6 @@
   ./services/web-servers/jboss.nix
   ./services/web-servers/tomcat.nix
   ./services/x11/desktop-managers/default.nix
-  ./services/x11/desktop-managers/gnome.nix
-  ./services/x11/desktop-managers/kde4.nix
-  ./services/x11/desktop-managers/none.nix
-  ./services/x11/desktop-managers/xterm.nix
   ./services/x11/display-managers/default.nix
   ./services/x11/display-managers/auto.nix
   ./services/x11/display-managers/kdm.nix
diff --git a/modules/services/x11/desktop-managers/default.nix b/modules/services/x11/desktop-managers/default.nix
index 8afe14b743d..04fda6d2232 100644
--- a/modules/services/x11/desktop-managers/default.nix
+++ b/modules/services/x11/desktop-managers/default.nix
@@ -1,22 +1,23 @@
-{pkgs, config, ...}:
+{ config, pkgs, ... }:
+
+with pkgs.lib;
 
 let
-  inherit (pkgs.lib) mkOption mergeOneOption mkIf filter optionalString any;
+
   xcfg = config.services.xserver;
   cfg = xcfg.desktopManager;
 
   # Whether desktop manager `d' is capable of setting a background.
   # If it isn't, the `feh' program is used as a fallback.
   needBGCond = d: ! (d ? bgSupport && d.bgSupport);
+  
 in
 
 {
-  imports = [
-    ./kde4.nix
-    ./gnome.nix
-    ./xterm.nix
-    ./none.nix
-  ];
+  # Note: the order in which desktop manager modules are imported here
+  # determines the default: later modules (if enabled) are preferred.
+  # E.g., if KDE is enabled, it supersedes xterm.
+  imports = [ ./none.nix ./xterm.nix ./gnome.nix ./kde4.nix ];
 
   options = {
   
@@ -24,11 +25,11 @@ in
 
       session = mkOption {
         default = [];
-        example = [{
-          name = "kde";
-          bgSupport = true;
-          start = "...";
-        }];
+        example = singleton
+          { name = "kde";
+            bgSupport = true;
+            start = "...";
+          };
         description = "
           Internal option used to add some common line to desktop manager
           scripts before forwarding the value to the
@@ -48,16 +49,15 @@ in
         };
       };
 
-
       default = mkOption {
-        default = "xterm";
+        default = "";
         example = "none";
-        description = "
-          Default desktop manager loaded if none have been chosen.
-        ";
+        description = "Default desktop manager loaded if none have been chosen.";
         merge = mergeOneOption;
         apply = defaultDM:
-          if any (w: w.name == defaultDM) cfg.session.list then
+          if defaultDM == "" && cfg.session.list != [] then
+            (head cfg.session.list).name
+          else if any (w: w.name == defaultDM) cfg.session.list then
             defaultDM
           else
             throw "Default desktop manager ($(defaultDM)) not found.";
diff --git a/modules/services/x11/display-managers/default.nix b/modules/services/x11/display-managers/default.nix
index 197ba7631e9..d2b01a61ba8 100644
--- a/modules/services/x11/display-managers/default.nix
+++ b/modules/services/x11/display-managers/default.nix
@@ -23,7 +23,7 @@ let
 
       # The first argument of this script is the session type.
       sessionType="$1"
-      if test "$sessionType" = default; then sessionType=""; fi
+      if [ "$sessionType" = default ]; then sessionType=""; fi
 
       ${optionalString (!cfg.displayManager.job.logsXsession) ''
         exec > ~/.xsession-errors 2>&1
@@ -180,7 +180,9 @@ in
         apply = list: rec {
           wm = filter (s: s.manage == "window") list;
           dm = filter (s: s.manage == "desktop") list;
-          names = concatMap (d: map (w: d.name + " + " + w.name) wm) dm;
+          names = flip concatMap dm
+            (d: map (w: d.name + optionalString (w.name != "none") (" + " + w.name))
+              (filter (w: d.name != "none" || w.name != "none") wm));
           desktops = mkDesktops names;
           script = xsession wm dm;
         };
diff --git a/modules/services/x11/display-managers/kdm.nix b/modules/services/x11/display-managers/kdm.nix
index 74b430e298c..7dd979376d6 100644
--- a/modules/services/x11/display-managers/kdm.nix
+++ b/modules/services/x11/display-managers/kdm.nix
@@ -26,6 +26,8 @@ let
 
       [X-:*-Core]
       ServerCmd=${dmcfg.xserverBin} ${dmcfg.xserverArgs}
+      # KDM calls `rm' somewhere to clean up some temporary directory.
+      SystemPath=${pkgs.coreutils}/bin
       # The default timeout (15) is too short in a heavily loaded boot process.
       ServerTimeout=60
       # Needed to prevent the X server from dying on logout and not coming back: