This tutorial will explain you how you can put windows live messenger home screen in System Tray instead of the TaskBar which is default in Windows 7.
- Close Windows Live Messenger
- Go to
"C:\Program Files\Windows Live\Messenger"
- Right-click on msnmsgr.exe and select Properties
- Select the “Compatibility” Tab and CHECK the “Run this program in compatibility mode”. Now from the dropdown menu choose the “Windows Vista” and click OK.
And VOILA 
now your messenger will minimize in the system tray instead of the taskbar!!!
