An MD-88 flight crew experienced loss of FMC and RNAV capability departing ATL. They were unsuccessful in restoring the FMC and continued to destination.

Narrative

During takeoff on Runway 9L at liftoff we had both maps fail. When sent to ATL departure we told them we were unable to comply with the RNAV departure and would require vectors until we could run the checklist. We completed the after takeoff checklist I turned the autopilot on and I called for the FMC fail checklist. We completed the QRH and were unable to recover RNAV. I gave the aircraft and radios to the First Officer and I contacted flight control and maintenance. Maintenance gave me some things to try but was unable to recover RNAV. Flight Control and I agreed that we could continue the flight if ATC agreed and I asked for new fuel burn and time. I contacted ATC and we got a new clearance to comply with no RNAV and RVSM. No other problems occurred until descent. At 15;000 FT MSL we were in the clouds in light rain. There was nothing but green on the radar. We were hit by lightning twice in 10 seconds. The aircraft systems were normal and the rest of the flight was fine. I sent an ACARS to Dispatch and called them and Maintenance on the ground.