Actually, I dislike the Preferred Pro.
There are two revisions of the basic Dell USB rubber dome keyboard - one is dark gray and has XP-spec Windows keys, the other is black and has Vista-spec Windows keys.
All of the Vista ones start out very mushy, and get worse within a year.
Some of the XP ones start out pretty crisp, and stay crisp for years. And, I think they're better than the Preferred Pro (well, at least the Lenovo-branded version of it.)