To capture the output, just print to file. Some applications let you select that when you print. If yours doesn't, go to printer Properties, click on the Ports tab, and select File. You will be then prompted for a file name when you print. If you want to use the same file name every time, without a prompt, go to the Printers and Faxes control panel. From the File menu select Server Properties. Click on the Ports tab, then on the Add Port button. Select Local Port from the list and click on New Port. Now enter the full path name of the file you want to use (e.g. C:\Temp\print.prn)
Assuming the output is in PCL, you can convert it to many different formats, using a number of different utilities. See for example:
http://www.swiftview.com/swiftconvert.htm