You could just get a good t8 fluorescent or cfl fixture in the a color spectrum of 5000k - 6500k. I wouldn't go with a dual t5HO mainly because they produce quite a bit of heat. Look up lighting for low light planted tanks and you'll find some pretty good articles. If you want to spend a little more, led lights would be great as they produce next to no heat. For leds, the marineland doublebright led is supposedly sufficient for low light plants.
In most cases, aquarium plants (even low light ones) won't grow very fast with just ambient room lighting, but a bright room with lots of windows they would do just fine (only problem with a room with many windows is it can heat up quite a bit).