That’s a tiny bit baffling since Box.net offers a web-based file storage and sharing service. A while back I remember reading something about a desktop client for Box.net but I’m not sure that ever materialized. So perhaps by “pre-installed,” Box.net means “there’ll be a shortcut to our web site on the desktop.”
It’s also possible that Dell customers will be able to sign up for premium Box.net accounts for a reduced fee. The service normally provies free account holders with 1GB of free storage while you have to pay if you need additional storage space. Asus has begun offering up to 20GB of free online storage to Eee PC customers. Perhaps this is Dell’s answer.