pg_dump slow

Hi

i´m using PostgreSQL on windows 2000, the pg_dump take around 50 minutes
to do backup of 200Mb data ( with no compression, and 15Mb with
compression), but in windows XP does not pass of 40 seconds... :(

This happens with 8.1 and version 8.0, somebody passed for the same
situation?

It will be that a configuration in the priorities of the exists
processes ?  in Windows XP the processing of schemes goes 70% and
constant accesses to the HardDisk, while that in windows 2000 it does
not pass of 3%.

thanks

Franklin