Recovering db from cracked server

I own a server that was recently cracked by, I presume, an incompetent
script kiddie. Minutes after he bravely tagged the web site, the
server went down hard and would not boot. I've built a new system.

I need to recover a postgresql 7.2 database from the old hard drive,
which is still readable. The postgresql data directory is intact. The
latest version of postgresql is incompatible with 7.2.x, so I compiled
postgresql-7.2.7 and attempted to run

postgres -D copy_of_old_data_dir

The error response (on stdout) is

DEBUG: database system was shut down at 2005-02-20 21:54:33 CST
DEBUG: checkpoint record is at 0/5CCA0AC
DEBUG: redo record is at 0/5CCA0AC; undo record is at 0/0; shutdown
TRUE
DEBUG: next transaction id: 73360; next oid: 59092
DEBUG: database system is ready
FATAL 1: Database "postgres" does not exist in the system catalog.
DEBUG: shutting down
DEBUG: database system is shut down

Am I close? or is this approach doomed? Suggestions gratefully
accepted.

Don Doumakes
Email: doumakes at loganet dot net
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