LargeObjects problems

Hi:

I have inserted a LargeObject using LargeObject Postgres API but when I
get back the bytes they are changed in some way. For instance, if I
insert the bytes of a zip or a jpg file (and they are ok, because I can
view the contents), when I retrieve the bytes from the database and
create new files with the bytes, the original files and the new ones
differ. They contain the same number of bytes, but they differ. No
longer winzip or iexplorer open the new files, and diff says the files
differ.
I'm using windows version of postgres, and jdk1.4.1_01
The field's data type is oid, of course

By the way, if I use the JDBC standard API (setBytes o setBinaryStream
using bytea) I get an OutOfMemoryError with files with size equals or
larger than 10Mb.

Regards,
Gustavo Muñoz.