To upgrade the PostgreSQL database software used by VPOP3

1. stop VPOP3
2. backup the database (http://wiki.pscs.co.uk/how_to;backup_vpop3#manual_database_backup1)
3. uninstall PostgreSQL (from within Windows) if necessary
4. rename the VPOP3\pgsql folder to something else
5. download PostgreSQL (latest from http://www.enterprisedb.com/products-services-training/pgdownload#windows)
6. install PostgreSQL (preferably into the VPOP3\pgsql folder, but that's not critical)
7. restore the backup you did earlier (http://wiki.pscs.co.uk/how_to;restore_a_database_backup)
8. restart VPOP3