How can I tell if autovacuum is running on Windows Server 2003 for my PGSQL database?
There are columns in pg_stat_user_tables that list when the last autovacuum and autoanalyze was run on a table - that's a good starting point. And of course, the logfile will contain information about what autovacuum is doing.
You can look specifically at the postgres.exe processes with a tool like Process Explorer. There will be a mutex specifically named to emulate the ps commandline information available on Unix. It should be easy to find. And you can just search for "autovacuum" to make sure it's running.