Share Screen between Laptops i.e, Mirroring or Extending

Do with Free Software ZoneScreen.....Awsome

ZoneScreen can do both works:
1)extending your desktop workspace using another computers in the network
2)mirror local desktop to another computer in the network (without control)

ZoneScreen consists of two parts:
a) ZoneScreen Virtual Display Driver which is visible to Windows just as normal video card with monitor attached to it, and
b) user-mode ZoneScreen Wizard which is responsible for capturing image (running at server side), transmitting it over the network, and drawing it at another computer (running at client side).

Note:
1) Server machine have Virtual Display Driver installed and ZoneScreen Wizard running in server mode. Another machine acts only as external display and called client. Client machine have only ZoneScreen Wizard running in client mode.
2) In case we are interested only in mirroring desktop image, we do not need to install Virtual Display Driver. And if we are extending desktop we could install ZoneScreen Virtual Display Driver

Step 1: Download ZoneScreen ( For XP: http://www.zoneos.com/downloads/zonescreen/fre_wxp_x86_en.zip, For Vista:http://www.zoneos.com/downloads/zonescreen/fre_wlh_x86_en.zip, For 2K: http://www.zoneos.com/downloads/zonescreen/fre_w2k_x86_en_1090.zip), unpack it.

Note: Step 2 to 3 required for only Extending Desktop. You can skip if you want only mirror the desktop

Step 2: Open up control panel - New Hardware installation - next - Yes, new hardware is connected - last row in the list (add new device) - Manual hardware installation, selected from the list - Show all hardware - Install from the disk - chose the folder with unpacked ZoneScreen - select file zonescreen.inf.

Step 3: Go to the Desktop Properties - Settings tab - you should see a small third display appeared in monitor box- select it or choose from drop down "zonescreen virtual display driver" -  set the flag "expand desktop to this display" - apply.

Step 4: Open up the folder with unpacked ZoneScreen in Server/Master Machine- run zserver.exe - select Act as a server - hit Next - in the second combo-box select your virtual display (for Mirror select \\. \Display1 and for Extend select other value) - in the third combobox select "800x480x16@42" - hit Next - [Select from the top menu "File - Save configuration to run at startup" (that's because XP resets secondary display settings after restart)] - click start

Step 5: Open up the folder with unpacked ZoneScreen in Client/Slave Machine- run zserver.exe - select Act as a client - hit Next - enter Server host name - Next

             second display is ready. Serve it with beer and nuts :)

Note:
1) In case of Mirroring from ZoneScreen, Client user only watch, can't control server machine but by RealVNC client user can control. 
2) If you are using ZoneScreen for Extending Desktop and now you want to mirror your desktop(to show both) then use any other image redirecting software. For example, RealVNC is capable of using ZoneScreen Driver update API.

Copy the content from these links http://www.zoneos.com/zonescreen.htm , http://talk.maemo.org/archive/index.php/t-25843.html

Many Many thanks to Vasily Tarasov (developer of ZoneScreen software)

other sharing software http://www.kimpl.com/1103/free-tools-to-manage-multiple-displays-and-computers/