Can I copy data file and use it with other version of Postgresql

We are facing a probelm and its very urgent to sort it out. Please Help.
The database server unexpectedly shutdown down due to power failure. On reboot, Postgresql server fails to start giving following Error:
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LOG: could not create IPv6 socket: Address family not supported by protocol
FATAL: database files are incompatible with server
DETAIL: The database cluster was initialized with PG_CONTROL_VERSION 0, but the server was compiled with PG_CONTROL_VERSION 72.
HINT: It looks like you need to initdb.
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we are using Mandrake Linux 9.1 and two version of Postgresql Version-7.4.2 and Postgresql Version-7.3.2 is installed
The Data directory is initialised with postgresql-7.4.2.
Postgresql -7.3.2 is not used .Postgresql-7.4.2 is used for managing Postgres Server.

Can I copy the Data Files and use tht Data with other Version of Postgresql ??.

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