Popular Chronic Dev Team have updated their tool with support for Windows, there was loads of traffic on the Greenpois0n website yesterday which resulted in the server not functioning properly, but finally they have managed to solve all the problems with the server and are back to Jailbreak your iPhone 4S and iPad 2.
There are many people waiting for these tools from a long time and though the mac versions have already been released the windows users always have to wait but now the wait is over, you can download it directly from here. As this is the untethered jailbreak you will not have to worry about loosing root when rebooted, so go ahead and enjoy.
Source: CultofMac