Rebuilding portions of the technology infrastructure of financial services firms whose offices were destroyed in the World Trade Center attack will cost $3 billion to $5 billion, according to early evaluations by the TowerGroup. Larry Tabb, vice president-securities and investment research practice, said it would cost about $3.2 billion to replace the technology destroyed. About $1.7 billion of that would be for hardware, and $1.5 billion would cover the services and software to install and connect networks, operating systems and applications infrastructures. TowerGroup estimated another $300 million would be needed to replace printers, hubs, switches, data storage and networking hardware, and $1.5 billion to install, configure and manage the implementation of replacement equipment. TowerGroup estimates much of the spending will occur in the next 12 to 24 months.