• One president fired a cabinet member, thereby violating an Act of Congress written specifically to keep that particular person in his job.
• One president got a blowjob and lied about it under oath.
• One president violated the 4th Amendment rules (and subsequent Supreme Court rulings) on search & seizure as they apply to U.S. citizens.
There are two reasons why the third of those almost certainly won't result in an impeachment case, even though it is arguably the highest "high crime" of the three (and even though if Bill Clinton had been the president in question in the third case, with the Congress of 1998-1999 in power, he likely would have been tried & convicted). The first reason is obvious: Because the President is a highly-partisan Republican and both houses of Congress are controlled by highly-partisan Republicans who are generally zealous backers of him, his actions, and his policies.
The second reason may be less obvious: Because even highly-partisan Democrats are not eager to live through up to three years of reign by President Cheney (and then possibly another four). Cheney hasn't exactly kept his nose clean (q.v. the national energy policy committee and some conveeeeenient Halliburton ties), but if he has done anything impeachable, he has been extra careful to not leave trails of evidence and to not publicly admit to doing any even arguably illegal actions, so it is extremely unlikely that we would lose both the President and Vice-President in a short span, as happened with Nixon & Agnew, which is what would likely need to happen for people to seriously support impeachment proceedings against Bush.
Feudalism: Serf & Turf