Feldman, vice president of the shared data center at Securities Industry Automation Corp. (SIAC) in New York, made surprise calls to the the vendors being considered for the migration project. He told the president of Clerity Solutions Inc., one of the vendors, that he was going to send the company some coding work and then fly to its Phoenix development center within 24 hours to examine the end results.

Some of the other vendors balked at such tests, Feldman said. But Clerity completed the work and was hired.

That taught Feldman a lesson about dealing with prospective migration vendors. "Don't be afraid to challenge them with a final test," he said. "And that test should [make them] stand on the merits of what they have told you so far. If they told you that they can migrate so much code or so many screens in a certain time frame, put them to the test."

Nick Sementilli, CIO at The Reader's Digest Association Inc. in Pleasantville, N.Y., is also involved in a mainframe migration process. But he has taken an entirely different approach by outsourcing his mainframe to Infocrossing Inc. under a contract that was signed in 2004 and recently extended by three years to 2012.

SIAC's migration is moving ahead on a fixed schedule and is due to be completed by the fourth quarter. For Reader's Digest, the migration could last five more years, according to Sementilli, who has stopped developing new applications for the mainframe and plans to gradually port existing applications to Unix.