Not sure how many tables you are talking but if it is a limited number of reasonable volume you might try looking for a copy of OLELOAD. It was an app that used to be delivered with TTU apps and provided a point-and-click mechanism for pointing to a source and target database and it would generate the extract and load scripts for you. I've also used SAS to do this.
If you are talking an entire database being transferred and it's an Oracle source I know that there is an entire library of Oracle migration utilities available somewhere. Maybe one of our colleagues can turn you on to how you might obtain them.
Your "another dw system" is Teradata, Oracle or something else? What size and is it a one time transfer or recurring? Teradata has a set of utilities for TD-TD transfer called TTU that includes Teradata FastExport, FastLoad, MultiLoad, TPT and etc No conversion has to be done.
If you are transferring data from other database vendor you might need to do some data conversion. For instance Oracle Date type has both date and time while Teradata has only date portion. TD Loader could fail. Also it could be a challenge getting a lot of data in text files from some databases such as Oracle. Check the pdf discussing similar issues and how to overcome: http://www.wisdomforce.com/resources/docs/FastReaderBestPracticesforTeradata.pdf