Sn0wbreeze 2.5 was released a day ago and now the Sn0wbreeze 2.5.1 will be released, probably today, as said by iH8sn0w, the developer behind the jailbreaking tool. Sn0wbreeze 2.5.1 may bring in custom boot animations along with it and some fixes also.
We have already written a detailed guide on how to use Sn0wbreeze 2.5 to jailbreak iOS 4.3.1 untethered on Windows. Mac users could use out PwnageTool 4.3 guide also for the same purpose. Else, if you don’t want to preserve the baseband, you could use our Redsn0w 0.9.6RC9 guide.