And there in lies the problem. 1st year webmasters shouldn't be buying PR7 domains :).
Like buying a car "as-is" (from a private owner, not dealership) you had best bring a good "web mechanic" with you when buying that "great deal" or your SOL.
And at the VERY least have a good legal contract stating, "blah blah backlinks in place for X months" ..."blah blah escrow account"
Sorry but that's just basic business.