Upgraded to Red Hat 7.1, now my DB is toast?

I had PGSQL up and running fine on RH6.2 (whatever version comes with
RH6.2). For some fool reason, I thought I'd upgrade to 7.1. While
reconfiguring my system after having almost all of my settings
mysteriously vanish, I finally get to starting up postmaster and get
this error:

/usr/bin/postmaster does not find the database system. Expected to find
it in the PGDATA directory "/var/lib/pgsql/data", but unable to open
file with pathname "/var/lib/pgsql/data/base/template1/pg_class".

No data directory -- can't proceed.

Ack. The /var/lib/pgsql/data/base does exist but there is no template1
dir... Does this mean that DBs made with 6.whatever are incompatible
with 7.whatever? And if so, is there a way to recover/upgrade/save the
db I already have? Thanks in advance for any advice. Later,

J. J. Franzen