The D50 has a selectable USB interface.
Either "mass storage" or PTP.
My guess is.....it is set for mass storage.
If so, you should be able to look at and download the camera files using Windows explorer.
Windows should see the camera as a hard drive.
Of course the camera has to be connected to the computer and turned-on and in playback mode.
If you want to download using the programs you mentioned, you have to have the USB interface in PTP mode.
Check you camera manual for details.
I'm unable to transfer photos from my Nikon D 50 DSLR to my PC. I'm using Windows XP and the transfer dosn't work either using the MSFT software or with Photoshop Elements 2.0. Some, but not all, of the photos were shot in RAW format. This is thefirst time that this kind of problem has occurred.