The ability to build playlists across albums etc is also a draw for me.
My PC based system is in the same room as my pool table, so the ability to develop a couple of playlists dedicated to activities is also nice.
The other one about PC based audio, and depending on how you intend to access it, is the ability to leverage that centralized library to more than one system - networked music players throughout the house and the ability to control that playback into multiple zones from anywhere on that network.