Ok, finaly sucess :-)
Info is here:
http://forum.gsmhosting.com/vbb/show...34&postcount=2
Simply download rar or zip file, do what Malik say with windows settings, remove rar or zip extension and replace with ipsw.
So if You have iPhone2_1_3.0_7A341_Restore.rar change it's name to: iPhone2_1_3.0_7A341_Restore.ipsw
Good luck all :-)
Thank You.