untethered jailbreak for 5.0 (9B179b) or upgrade?

Hi, Im wondering if I can perform an untethered jailbreak on my atv2 running 5.0.  The device has never been jailbroken before.  I do plan on taking it from place to place so I need an untethered jailbreak.  Any help is greatly appreciated, I have never jailbroken an atv2 before, only an atv1.

so, based on another thread i read that tinyumbrella can check the software version of the atv without plugging it into the tv. however tinyumbrella says the software firmware is 5.1 and the apple tv about screen says 5.0 (4099)

which is correct?

i tried to save my shsh for the heck of it and it looks like tinyumbrella is telling me im too late.