Forget about uploading, for now.
In NetMD and older MD's you cannot upload the files digitally, you can only record to the PC in real time. In the new HI-MD's you can upload, but only to a secure sony file that will not allow you to play it on a diffrent computer, let alone convert to WAV/MP3.
A soon-coming sonicstage software update may change that but it is not assured.
If you still want a robust MD than look at the middle ranged/High-end models.
http://www.minidisc.org/part_Sony_MZ-N920.html
http://www.minidisc.org/part_Sony_MZ-N707.html
http://www.minidisc.org/part_Sony_MZ-N910.html
http://www.minidisc.org/part_Sony_MZ-NH1.html
http://www.minidisc.org/part_Sony_MZ-NH900.html