I run a Server on my laptop too, have an old inter 2 duo with 2ghz and 3 ram with low clockrates... but so far the server runs fine, mostly is the internetspeed whats make it better foor tekkit you can never have enough ram^^
as in my opinion tekkit light is quite buggy and missed a lot of old stuff or most mods doesnt are supported or developed anymore i would stay on the old server as far as you dont wann open anew one, as far as i seen theres no energy links and the engines are heavily buging on my map so i am back to classic, anyway if you install a linux server operating system you could also get a speed boost because it dont has to run the whole graphical stuff