Thx BSchwarz,
one more thing, every Developer will have he's own instance of the VM,
I mean if one developer "dev1" created a word document "word1" inside the image and the scd developer 'dev2" created an excel "excel1".when the both shutdown the VM and at later time comes back, dev1 will find the "word1" on the VM without seeing excel1 of dev2.
It's like Windows vista centralized desktop but for Win XP.
Thx.