In order to migrate a database from POSTGRES to MS SQL Server use a very powerful set of tools called Data Transformation Services (DTS). These tools can help you perform these tasks in Microsoft SQL Server 2000. DTS can help you import, export, and/or transform data from various sources to single or multiple locations. Please refer to a very good illustrative article for all details at TechRepublic.
In order to migrate data from postgres please install an ODBC driver for postgres so that the DTS can communicate with the postgres. Once this is done use import/export or copy database wizard available in MS SQL Server. Create a DTS job on your MS SQL Server and schedule it using dtsrun.
Upgrade to SQL Server 2005
If you are migrating to SQL Server 2005 you can use Import/Export wizard provided by Integration Services package (SSIS) or even the Data Transformation Services (DTS).
In order to use SSIS you need to have SQL Server Business Intelligence Development Studio installed. A very nice tutorial that illustrates how to use the import/export on SSIS is available at Database Journal written by Gregory A. Larsen
Good resource on Postgres.