Changing column types

Owing to a problem with the way access and a couple of other programs
I've found handle text columns in PG as something they call 'memo', I
want to change all of the text columns in my database to varchar.
There's about 600 text columns all up, so I'm looking for a quick way of
  doing this.

Is there any way, using the system catalogues - pg_tables, pg_attributes
etc that I can automatically change all text type fields to varchar or
am I better of just recreating the schema?

--
Paul Lambert
Database Administrator
AutoLedgers