If you have a computer upstairs and one downstairs connected using a wireless router how do you transfer music files on one to the other?

Yeah it will work fine, but you need a wireless network card for both your desktop or laptop but you can plug in a ethernet cable into one and leave one wireless and it will still work. All you do is drag the folder or songs you want to share and put it into your a shared folder or you can just select to share the folder(there should be a option to do so or you may have to right click it and select share). Then go to your other computer and go to its network neighborhood (my network places) and click view workgroup computers. If you don't see your other computers name there then you need to click view entire network (Microsoft Windows network), if you still don't see it then try to set a home network wizard or change your workgroup. Once you see the computers name or description then double click it. If it ask for a passWord then you will have to play around with the network settings for the other computer. If you get in select the folder that you put the music in or the folder that you shared and select the music you want, copy it and then paste it to your hard drive (a folder or just your desktop). Then you will be done.