Snowbreez is yet another tool for jailbreaking iPhone and iPod Touch, it's similar to other jailbreaking tools like blackra1n, redsn0w and PwnageTool. All these tools are used to create custom .ipsw files to jailbreak iPhone/iPod. The enhancement Sn0wbreez brings is that it works on Windows 7/Vista and XP. If you are unlucky to jailbreak your iPhone with earlier mentioned tools, you can give Snowbreeze a try to see if it helps in jailbreaking your iPhone.