The tactical problem with impeachment has been that progressives want to start at the top. Prosecutors have always found it more efficient to unravel criminal conspricies from the bottom up. By attacking the weaker members of the gang first, the stronger ones can eventually be brought down.
Gonzales is an ideal target for impeachment because he has lied under oath. His trial and removal from office will start an avalanche of investigations that may well take down Bush and Cheney too. The dirty hands of Gonzales are implicated in some of the worst abuses of civil liberties in recent American history. He should be removed from office as soon as possible, not only to end his malign role in the government, but to find evidence leading to the impeachment of Bush and Cheney.