I'm trying to solve a storage space and backup problem for a friend with a rMBP. She needs an external drive for her time machine backup. She also needs to keep her iTunes Music folder on an external drive because the internal drive is too small. Now, she doesn't want a locally attached drive, which is why I'm thinking about a Time Capsule. But she already has a wifi router so it seems unnecessary to pay for an extra router. Is there any reason to go with the Time Capsule over another NAS etc? Also, in the past I have mounted a drive with my iTunes Music Folder over a wired Gigabit network, and it was very slow. I can imagine it is even worse over wifi? Is it realistic to use a Time Capsule or NAS over wifi in place of a directly attached drive? She wants to have to drive mounted on her desktop and be able to transfer files as easily as if it was attached via USB, and perhaps even work on documents or photos from the networked drive. Will this be very slow and unreliable? She also has an iMac where she could share an external drive over the network. Would this work in the same way and with then same speed as a Time Capsule or NAS? And would Time Machine be able to back up to iy over wifi? Any thoughts or comments would be greatly appreciated.