Do you already have the right software for your data cable? I have the same phone, but I don't use a data cable. I pay for the Vision Plus pack and use
www.rumkin.com/tools/sprint to transfer ringtones, wallpaper, and games to my phone. The downloads are free if you have one of the Vision packages included in the plan, otherwise you pay 2cents/kilobyte. If you enter your phone number, you will also use one text message.
I will look again later, but just from browsing here and google, I didn't find any software compatible with our phones for ringtones and wallpapers, only address book type stuff.