Changing prosecutors in mid-stream is at very best a delaying tactic, at very worst, which is always to be assumed with the Repugs, Noel Hillman was playing ball too hard, being way too aggressive, so dubya/gonzalez kicked him of the Abramoff case and into a judgeship.
An exact parallel was Nixon's, another Repug of course, Saturday Night's Massacre:
http://en.wikipedia.org/wiki/Saturday_Night_Massacre
Expect the replacement prosecutor to be as totally politicized as Ken Starr, meaning, the new prosecutor will be a limp when trying to penetrate Abramoff's complex corruption, and will not go after the numerous Repug congressmen that Abramoff very probably did corrupt deals with.