Clinton was not accused of stealing the election. People questioned whether they wanted him as president, but they did not question whether he had actually won according to the rules in place at the time. The current accusations are that Bush didn't actually win the election, but that voting irregularities and political pressure all the way up to the Supreme Court helped install a pretender to the presidency.
Had Clinton's opponenets succeeded in their aims, he would have been removed from office. If Bush's opponents are successful, his presidency could theoretically be declared to have never been valid. The implications for what to do about irreversible policy decisions (Tax refund checks are going out soon, etc.) and international relations (Kyoto Accord, etc.) are vast and unknown. There is not, that I'm aware of, any existing law governing what to do if a president's term is declared to have been invalid. Would all legislation he signed become null and void? Would any decisions regarding pardons/clemency be reversed? There is no precedent.