The recent government pursuit of Enron, Frank Quattrone, Arthur Anderson, and any number of other firms has established one "principal" being followed by the government in all of these cases: They will let large corporations off the hook with fines but no criminal charges IF the corporation agrees to sell out all of its employees. A large part of this deal, being cut all over the place (and for which Arthur Anderson was destroyed mainly for not agreeing to) is that the corporation will waive attorney client privelege for discussions between employees and corporate attorneys. Frank Quattrone has been tried twice and will likely get tried a third time mainly based on evidence of emails he sent back and forth with corporate council. Tom Kirkendall has other examples.
Ten years ago, I would have naively given the advice "don't break the law." Still good advice, but nowadays in business its hard to tell just what is the law and what is illegal (antitrust is a great example). So my new piece of advice is "when in doubt, don't use corporate council." Get your own lawyer. If the company will pay for it, all the better but do it even if it's out of your own pocket, because it is clear that corporate lawyers are NOT your lawyers, and they will cooperate with the corporation who employs them to put you in jail if that helps protect their real client who pays their salary.