You can't use the USB port to upload field recordings.. yet.. there are some dedicated people working to 'hack' that BS security feature on Sony's MD recorders...

You'll have to plug the headphone jack "Out" from the MD recorder to your "Line In" on your sound card... Then 'real time' record the tracks using whatever sound recording software you prefer (Cooledit for me)... That'll put the files on yer PC, and you can then tweak 'em as you see fit...