Thrift Savings Plan moving off mainframe

Thrift Savings Plan, a retirement savings plan for government employees, is moving off the mainframe, according to Government Executive:

Mark Hagerty, chief information officer for the TSP, noted that a two-year plan to upgrade technology capabilities is on track. Officials struck an agreement with Switch & Data of Tampa, Fla., in December 2008 to expand operations to a new data facility in Northern Virginia. The plan involves replacing mainframe computers with newer technology offering more memory and faster processors, consolidating and replacing servers, modernizing IT networks, and improving storage capacity.

Officials began moving equipment into the new center last month, Hagerty said. The new data center is expected to be fully operational by September.

I wonder if TSP seriously considered replacing old mainframes with new mainframes, or if the push was for x86 (or Unix) from the start.