checksum error from windows to linux

Hi all,
I'm a newbie to postgres, and I'm facing a few problems to start my postgres server.
Actually, I've retrieved a postgreSQL database from a postgreSQL server that was running on windows and I'm trying to load this database on a postgreSQL server that will be running on a linux mandrake platform. I downloaded the PostgreSQL 8.0.7 package, same version as the windows server, and copied the data directory from the windows server into the /usr/local/pgsql/data directory on my linux platform.
Then, I've tried to launch the server in the foreground with the command line :
/usr/local/pgsql/bin/postmaster -D /usr/local/pgsql/data
The error message was telling me that the value "French_France" for the locale "lc_messages" wasn't recognized by postmaster.
Then I've defined a locale alias in locale.alias for "French_France", but the checksum problem persists.
I suppose there's a deeper cause to this problem, involving the way the checksum is computed.
Is there a way to overcome the problem simply, for example re-compute the checksum before starting the server ?
Or may I initialize the server with an empty database with initdb, then postmaster and then recover the data without the checksum ? I'm really looking for this particular kind of recovering process.
Whatever, sorry for my difficulties of explanation, I'm really new to postgres and english isn't my mother tongue (I bet you've guessed it), and thanks a lot for any help !!
Antoine