Go to C:Windows/System32/drivers/etc and open the hosts file with notepad. At the bottom on a new line copy and paste this...
74.208.10.249 gs.apple.com
If there is already a line containing gs.apple.com then remove it but don't add anything. Make sure you save on exit and that iTunes is not running when you do it...
Redsnow did inject the iPad baseband for you but I'm not sure if it still does. Pwnage too for mac and snowbreeze for windows will create custom ipsw's but I have personally never used them...