diff --git a/modules/installer/cd-dvd/system-tarball-pc.nix b/modules/installer/cd-dvd/system-tarball-pc.nix
index 6162f599096f..9f81695452c2 100644
--- a/modules/installer/cd-dvd/system-tarball-pc.nix
+++ b/modules/installer/cd-dvd/system-tarball-pc.nix
@@ -21,13 +21,92 @@ let
       TOTALTIMEOUT 9000
 
     label nixos
-      MENU LABEL ^NixOS base through NFS
+      MENU LABEL ^NixOS using nfsroot
       KERNEL bzImage
-      append initrd=initrd ip=dhcp tnfsroot=IPADDR:/home/pcroot systemConfig=${config.system.build.toplevel} init=${config.system.build.toplevel}/initrd
+      append ip=dhcp nfsroot=/home/pcroot systemConfig=${config.system.build.toplevel} init=${config.system.build.toplevel}/init
+
+    # I don't know how to make this boot with nfsroot (using the initrd)
+    label nixos_initrd
+      MENU LABEL NixOS booting the poor ^initrd.
+      KERNEL bzImage
+      append initrd=initrd ip=dhcp nfsroot=/home/pcroot systemConfig=${config.system.build.toplevel} init=${config.system.build.toplevel}/init
 
     label memtest
       MENU LABEL ^Memtest86+
-      KERNEL memtest.bin
+      KERNEL memtest
+  '';
+
+  dhcpdExampleConfig = pkgs.writeText "dhcpd.conf-example" ''
+    # Example configuration for booting PXE.
+    allow booting;
+    allow bootp;
+    
+    # Adapt this to your network configuration.
+    option domain-name "local";
+    option subnet-mask 255.255.255.0;
+    option broadcast-address 192.168.1.255;
+    option domain-name-servers 192.168.1.1;
+    option routers 192.168.1.1;
+    
+    # PXE-specific configuration directives...
+    # Some BIOS don't accept slashes for paths inside the tftp servers,
+    # and will report Access Violation if they see slashes.
+    filename "pxelinux.0";
+    # For the TFTP and NFS root server. Set the IP of your server.
+    next-server 192.168.1.34;
+    
+    subnet 192.168.1.0 netmask 255.255.255.0 {
+      range 192.168.1.50 192.168.1.55;
+    }
+  '';
+
+  readme = pkgs.writeText "readme.txt" ''
+    Let all the files in the system tarball sit in a directory served by NFS (the NFS root)
+    like this in exportfs:
+      /home/pcroot    192.168.1.0/24(rw,no_root_squash,no_all_squash)
+
+    Run "exportfs -a" after editing /etc/exportfs, for the nfs server to be aware of the
+    changes.
+
+    Use a tftp server serving the root of boot/ (from the system tarball).
+
+    In order to have PXE boot, use the boot/dhcpd.conf-example file for your dhcpd server,
+    as it will point your PXE clients to pxelinux.0 from the tftp server. Adapt the
+    configuration to your network.
+
+    Adapt the pxelinux configuration (boot/pxelinux.cfg/default) to set the path to your
+    nfrroot. If you use ip=dhcp in the kernel, the nfs server ip will be taken from
+    dhcp and so you don't have to specify it.
+
+    The linux in bzImage includes network drivers for some usual cards.
+
+
+    QEMU Testing
+    ---------------
+
+    You can test qemu pxe boot without having a DHCP server adapted, but having nfsroot,
+    like this:
+      qemu-system-x86_64 -tftp /home/pcroot/boot -net nic -net user,bootfile=pxelinux.0 -boot n 
+
+    I don't know how to use NFS through the qemu '-net user' though.
+
+
+    QEMU Testing with NFS root and bridged network
+    -------------------------------------------------
+
+    This allows testing with qemu as any other host in your LAN.
+
+    Testing with the real dhcpd server requires setting up a bridge and having a tap device.
+      tunctl -t tap0
+      brctl addbr br0
+      brctl addif br0 eth0
+      brctl addif tap0 eth0
+      ifconfig eth0 0.0.0.0 up
+      ifconfig tap0 0.0.0.0 up
+      ifconfig br0 up # With your ip configuration
+
+    Then you can run qemu:
+      qemu-system-x86_64 -boot n -net tap,ifname=tap0,script=no -net nic,model=e1000
   '';
 
 in
@@ -58,8 +137,17 @@ in
       { source = pxeconfig;
         target = "/boot/pxelinux.cfg/default";
       }
+      { source = readme;
+        target = "/readme.txt";
+      }
+      { source = dhcpdExampleConfig;
+        target = "/boot/dhcpd.conf-example";
+      }
       { source = "${pkgs.memtest86}/memtest.bin";
-        target = "/boot/memtest.bin";
+        # We can't leave '.bin', because pxelinux interprets this specially,
+        # and it would not load the image fine.
+        # http://forum.canardpc.com/threads/46464-0104-when-launched-via-pxe
+        target = "/boot/memtest";
       }
     ];
      
@@ -69,19 +157,6 @@ in
   services.openssh.enable = true;
   jobs.openssh.startOn = pkgs.lib.mkOverrideTemplate 50 {} "";
 
-  boot.initrd.postMountCommands = ''
-    for o in $(cat /proc/cmdline); do
-      case $o in
-        tnfsroot=*)
-          set -- $(IFS==; echo $o)
-          # TODO: It cannot mount nfs, as maybe it cannot find 'mount.nfs'
-          mount $2 /mnt-root
-          ;;
-        *) ;;
-      esac
-    done
-  '';
-
   boot.kernelPackages = pkgs.linuxPackages_2_6_39;
   nixpkgs.config = {
     packageOverrides = p: rec {
diff --git a/modules/installer/cd-dvd/system-tarball.nix b/modules/installer/cd-dvd/system-tarball.nix
index 63c5a3117c45..a829b85b59fe 100644
--- a/modules/installer/cd-dvd/system-tarball.nix
+++ b/modules/installer/cd-dvd/system-tarball.nix
@@ -72,13 +72,16 @@ in
     inherit (config.tarball) contents storeContents;
   };
 
+  # Otherwise it will collide with the 'ip=dhcp' kernel autoconfig.
+  networking.useDHCP = false;
+
   boot.postBootCommands =
     ''
       # After booting, register the contents of the Nix store on the
       # CD in the Nix database in the tmpfs.
       if [ -f /nix-path-registration ]; then
         ${config.environment.nix}/bin/nix-store --load-db < /nix-path-registration &&
-        rm /nix-path/registration
+        rm /nix-path-registration
       fi
 
       # nixos-rebuild also requires a "system" profile and an