copying databases

 i have created a DB on one server using postgresql 6.5.3 and now i need
to move this DB to a machine running the postgresql 6.3 release (theone
shipped with debian slink).
I'd like to know how to move the DB from one server to the other and
eventually if there are any incompatibility passing from the new release
to a older one.
Thanks for replying to marco@tecnogi.com



.oesse.
--
------------------------------------------------------------------
+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|m|a|r|c|o| |g|i|a|r|d|i|n|i|
+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
TecnoGi spa                                   Tel. +39 0321 885422
Strada per Gravellona                         Fax  +39 0321 885333
Borgolavezzaro (NO)                         http://www.tecnogi.com
Key fingerprint = B5 B4 AA 91 89 50 43 8F  B1 6B C6 8C 34 79 5A 7F