Compare it to this one :
(off 'Autograph World' - extremely reputable site)
http://www.signaturepieces.com/auction/lot.asp?item=761
And I would say the one that person's trying to sell you is
authentic. The only subtle difference I can pick up is on the 's', but Jackson's signature has never been consistent. Just to show you what I mean, look how different the one below (from another reputable site) is to the two above - yet it was also obtained IP.
his is in the bottom right hand corner
I think it's safe to go for it.
