Don't forget the input of the sales and marketing departments. If you know that most of the computers in business X that you're trying to sell to are of a given spec, that can also make a marketing "request" of engineering :) You might ask how sales knows the type of computers a client has. Simply take a discrete look at the Dell/HP/whatever model number on a machine during a sales call- most companies have service contracts so they're not mucking around in the innards of their PCs (what you see is what you get).