diff --git a/configuration/rescue-cd.nix b/configuration/rescue-cd.nix
index 3c4b67e189c9..a69832d82691 100644
--- a/configuration/rescue-cd.nix
+++ b/configuration/rescue-cd.nix
@@ -19,7 +19,9 @@ rec {
       # The label used to identify the installation CD.
       rootLabel = "NIXOS";
       extraTTYs = [7 8]; # manual, rogue
-      extraModulePackages = [pkgs.aufs];
+      extraModulePackages = [system.kernelPackages.aufs];
+      
+      #kernelPackages = pkgs: pkgs.kernelPackages_2_6_25;
       
       initrd = {
         extraKernelModules = [
@@ -263,7 +265,7 @@ rec {
       { source = grubCfg;
         target = "boot/grub/menu.lst";
       }
-      { source = pkgs.kernel + "/vmlinuz";
+      { source = system.kernel + "/vmlinuz";
         target = "boot/vmlinuz";
       }
       { source = system.initialRamdisk + "/initrd";
diff --git a/system/options.nix b/system/options.nix
index c60044e85aed..37d6023eef38 100644
--- a/system/options.nix
+++ b/system/options.nix
@@ -75,13 +75,20 @@
       ";
     };
 
-    kernel = mkOption {
-      default = pkgs: pkgs.kernel;
+    kernelPackages = mkOption {
+      default = pkgs: pkgs.kernelPackages;
+      example = pkgs: pkgs.kernelPackages_2_6_25;
       description = "
-        Function that takes package collection and returns kernel 
-        package. Do not collect old generations after changing it
-        until you get to boot successfully. In principle, you can 
-        specify a kernel that will build, but not boot.
+        This option allows you to override the Linux kernel used by
+        NixOS.  Since things like external kernel module packages are
+        tied to the kernel you're using, it also overrides those.
+        This option is a function that takes Nixpkgs as an argument
+        (as a convenience), and returns an attribute set containing at
+        the very least an attribute <varname>kernel</varname>.
+        Additional attributes may be needed depending on your
+        configuration.  For instance, if you use the NVIDIA X driver,
+        then it also needs to contain an attribute
+        <varname>nvidiaDrivers</varname>.
       ";
     };
 
diff --git a/system/system.nix b/system/system.nix
index e65aef0a427e..c55e31914afd 100644
--- a/system/system.nix
+++ b/system/system.nix
@@ -33,24 +33,26 @@ rec {
 
   nix = config.environment.nix pkgs;
 
-  kernel = config.boot.kernel pkgs;
+  kernelPackages = config.boot.kernelPackages pkgs;
+
+  kernel = kernelPackages.kernel;
 
   rootModules = 
     config.boot.initrd.extraKernelModules ++
     config.boot.initrd.kernelModules;
 
 
+
   # Tree of kernel modules.  This includes the kernel, plus modules
   # built outside of the kernel.  We have to combine these into a
   # single tree of symlinks because modprobe only supports one
   # directory.
   modulesTree = pkgs.aggregateModules (
     [kernel]
-    ++ pkgs.lib.optional config.networking.enableIntel3945ABGFirmware pkgs.iwlwifi
-    ++ pkgs.lib.optional config.networking.enableIntel4965AGNFirmware pkgs.iwlwifi
+    ++ pkgs.lib.optional ((config.networking.enableIntel3945ABGFirmware || config.networking.enableIntel4965AGNFirmware) && !kernel.features ? iwlwifi) kernelPackages.iwlwifi
     # !!! this should be declared by the xserver Upstart job.
-    ++ pkgs.lib.optional (config.services.xserver.enable && config.services.xserver.videoDriver == "nvidia") pkgs.nvidiaDrivers
-    ++ pkgs.lib.optional config.hardware.enableGo7007 pkgs.wis_go7007
+    ++ pkgs.lib.optional (config.services.xserver.enable && config.services.xserver.videoDriver == "nvidia") kernelPackages.nvidiaDrivers
+    ++ pkgs.lib.optional config.hardware.enableGo7007 kernelPackages.wis_go7007
     ++ config.boot.extraModulePackages
   );
 
@@ -116,21 +118,24 @@ rec {
       { object = bootStage1;
         symlink = "/init";
       }
-    ] ++ (if config.boot.initrd.enableSplashScreen then [
-      { object = pkgs.runCommand "splashutils" {} ''
-          ensureDir $out/bin
-          cp ${pkgs.splashutils}/bin/splash_helper $out/bin
-        '';
-        suffix = "/bin/splash_helper";
-        symlink = "/sbin/splash_helper";
-      }
-      { object = import ../helpers/unpack-theme.nix {
-          inherit (pkgs) stdenv;
-          theme = config.services.ttyBackgrounds.defaultTheme;
-        };
-        symlink = "/etc/splash";
-      }
-    ] else []);
+    ] ++
+      pkgs.lib.optionals
+        (config.boot.initrd.enableSplashScreen && kernelPackages.kernel.features ? fbSplash)
+        [
+          { object = pkgs.runCommand "splashutils" {} ''
+              ensureDir $out/bin
+              cp ${kernelPackages.splashutils}/bin/splash_helper $out/bin
+            '';
+            suffix = "/bin/splash_helper";
+            symlink = "/sbin/splash_helper";
+          }
+          { object = import ../helpers/unpack-theme.nix {
+              inherit (pkgs) stdenv;
+              theme = config.services.ttyBackgrounds.defaultTheme;
+            };
+            symlink = "/etc/splash";
+          }
+        ];
   };
 
 
@@ -171,7 +176,8 @@ rec {
               
   # The services (Upstart) configuration for the system.
   upstartJobs = import ../upstart-jobs/default.nix {
-    inherit config pkgs nix modprobe nssModulesPath nixEnvVars optionDeclarations;
+    inherit config pkgs nix modprobe nssModulesPath nixEnvVars
+      optionDeclarations kernelPackages;
   };
 
 
diff --git a/upstart-jobs/default.nix b/upstart-jobs/default.nix
index d1ea5b255087..9f2c0f1b14da 100644
--- a/upstart-jobs/default.nix
+++ b/upstart-jobs/default.nix
@@ -1,4 +1,4 @@
-{config, pkgs, nix, modprobe, nssModulesPath, nixEnvVars, optionDeclarations}:
+{config, pkgs, nix, modprobe, nssModulesPath, nixEnvVars, optionDeclarations, kernelPackages}:
 
 let 
 
@@ -391,9 +391,10 @@ let
   )
 
   # Transparent TTY backgrounds.
-  ++ optional config.services.ttyBackgrounds.enable
+  ++ optional (config.services.ttyBackgrounds.enable && kernelPackages.kernel.features ? fbSplash)
     (import ../upstart-jobs/tty-backgrounds.nix {
-      inherit (pkgs) stdenv splashutils;
+      inherit (pkgs) stdenv;
+      inherit (kernelPackages) splashutils;
       
       backgrounds =