hey i just got iphone 4 and its 4.3 os and there is no untethered jailbreak for 4.3 so how do i update to 4.3.1 because itunes only wants me to update to 4.3.3
Well, there's really no way to tell, but if you update to 4.3.3 the baseband will still be the same as what you have now anyway. (I just did this myself a couple of weeks ago.) Basebands don't get updated every time iOS gets an update, so 4.3, 4.3.1, 4.3.2, and 4.3.3 all have the same baseband.
So you have no reason NOT to update, really.