Charting a successful career was the topic on Tuesday at Wal-Mart , where the company’s female officers staged a “Fortune Most Powerful Women” event and I interviewed two stars of the 2009 MPWomen rankings: Wal-Mart EVP of People Susan Chambers and Xerox CEO Ursula Burns.

Their bios tell the paths they chose. More inspiring and instructive, as they revealed on Tuesday, are the career paths they decided not to take.

Chambers, who joined Wal-Mart from Hallmark a decade ago, once dreamed of being a professional opera singer. Her mezzo-soprano might have been, but she didn’t love the idea of traipsing around the world as artists must do. “It’s still in my heart,” said Chambers, who now plays piano and sings–at home and at church–to lessen the stress of overseeing the largest private-sector workforce on earth. “Make sure you spend some percentage of time doing something that brings you joy,” she advised.

Burns told a story that few people know–how in 2001, she almost left Xerox.

Having joined Xerox as an intern in 1980, Burns by then had ascended to SVP in charge of manufacturing and supply-chain operations. a stellar rise, but Xerox was teetering–facing potential bankruptcy–and its CEO, a former IBMer named Rick Thoman, had lost the faith of investors and management.

Burns was outta there–or so she thought. She had lined up a job at a healthy, younger company and was about to move to Texas with her husband and two children when she got an unexpected call from a Xerox board member.

This director said to her: “If your spouse was old, but now they are sick, would you stay and care of him?”

Yes, of course, Burns replied.

“If you and your spouse both made it through to a long-term relationship, but now a young, ‘pretty’ suitor came along, would you stay in the relationship you’ve invested in–or leave for something new and unknown?”

Stay–absolutely, Burns told the director.

It was at that moment, Burns said, that she realized she was key to saving Xerox. And when she learned that the board was going to name Anne Mulcahy, another lifer who embraced the need for radical change, as the new CEO, Burns ditched her departure plan.

So, what was that healthy, younger company that almost lured Burns away? “Dell,” she told the Wal-Mart gathering.

And who was that Xerox director who persuaded her to stay? “Vernon Jordan,” said Burns, referring to the well-known Lazard lawyer who, besides serving on Xerox’s board, advises American Express , where Burns is a director. By sticking it out, she eventually made history: The Mulcahy-Burns succession, in July, was the first-ever woman-to-woman CEO handoff in the Fortune 500.