The way I do it is to use Windows Sound Recorder, a bit fiddly but it works well.
Start menu > progs > Accessories > Entertainment.
It only records 60 secs a time, so create & save a 'blank' 60 second file. Start again, then insert this blank 60 sec file as many times as you wish to create a new longer blank file. Have a play around, you can record /playback in 'cd' quality etc.