As part of the nightly extract, PA has several .r files which export the data from Intergy into csv files. It doesn't get all the tables, but it gets most. You should be able to import those text files created by the .r files into MS SQL (that is what PA does) or another environment.
Another choice would be to just export the data out of MS SQL after PA has loaded the data into it, if you would rather work with MS SQL than Progress 9.1D.