What are the current thoughts on when to change radiator coolant and hoses?

My '98 E320 has about 65K miles with original coolant and hoses. The car does not have any coolant problems. Should I flush the radiator and change the coolant/hoses? Or, should I leave well enough alone and not loosen up the potential rust and crud?

Thanks.

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Dave

1998 E320
2001 SLK320
2000 Lexus RX300