Those 4' shop lights distribute their light around sooo much they only make lankey stretchy plants(I know this from experience)
The T5 fixtures they make for growing have the bulbs closer together and have the reflective material closer to the bulb to send it down towards the plant...if you want to grow 5 plants look into at least a 250watt hps...or hell even a 150watt hps if you want to do a SCROG that would be fine...HTGsuppy.com has 150watt HPS complete systems for $66+shipping
http://www.htgsupply.com/Product-FLORALUX-150w-HPS-Mini-Grow-Light.asp
But really if you want to get any sort of yield off those 5 plants you need to upgrade your lighting severely...I wish I had rollitup to turn to when I tried using a shoplight once years ago lol