How best to manage IT infrastructure upgrades and their costs?

According to published reports, the long-planned computer systems upgrade at the US Federal Bureau of Investigation (FBI) will now take nine months longer and cost $26 million more than originally anticipated. The new estimates: $451 million in costs, to be completed in 2011. A previous attempt to upgrade its computer systems cost $100 million before the FBI declared it a failure. (Meanwhile, according to an inspector general’s report, many FBI agents were still sending photographs to Washington by overnight mail after the Sept. 11, 2001 attacks because those agents could not send e-mail attachments.) What operational steps does your business take, within and beyond IT, to ensure that its IT infrastructure is meeting and keeping pace with business needs? What roles can business operations play in ensuring that IT operations keep business-critical infrastructures agile and robust while keeping a lid on upgrade and maintenance costs?