For professionals planning to dictate at least 15 minutes per day who are acquiring a new system, the choice today is simple. Get the fastest system you can.
For those of you trying to use older versions of NaturallySpeaking, in general terms the system requirements for good performance were as follows:
On these older systems, Video RAM was a factor, with 8MB Video being better that the then-popular 1MB and 2MB video systems.
Sound cards were even more important then than today. Older laptop systems had notoriously bad sound systems in most cases.