There's some questioning of the testing method:
http://rrresearch.blogspot.com/2010/12/arsenic-associated-bacteria-nasas.html

Thanks for the link. You have to admire those ever-doubtful scientists and their search for truth.

I was going to mention (and now I wish I had, because it would make me look even smarter) that while arsenic has similar chemical properties as phosphorous the bonds that it forms are weaker. Being that it's valence shell is farther out, but that goes without saying.

Naturally.

Been real busy, but glad you guys are still here. Love that I can still hear this discussion. It's fun cause I don't know crap about this stuff, so I can easily dismiss your scientific fact with the fact the basis for live can even change,ipso facto, my levitating speaker wire can sound better! makes perfect sense really.

James that, 10-5.