Not OP, but my workplace computer is a Dell notebook with a Core i5 CPU underclocked to 750Mhz. I also use an X220i with a Core i3 CPU underclocked to 800MHz (because it will not run at lower speeds). Both offer excellent performance for everything I do. I never use the touchpad, both screens are fine IMO.

Things I do: small-scale data analysis and statistical modelling with Klong and Scheme, plotting graphs, compiling C programs, typesetting with Troff, browsing the Web with Javascript off.