It gives you poop.
lol actually if you're trying to figure out "low, med, high" lighting, it's not ruled by watts. Wattage is just how much electricity that it's taking to light the bulb. So it doesn't tell you how much your lights really are. Also incandescent's can't grow anything if that's what you're trying to achieve.
I really suggest you get two mini CFL (compact fluorescent light) around 9 or 10 watts each to replace them, it will give you a much better PAR rating which is what we measure our light with in the aquarium. PAR is parabolic aluminized reflector so basically we're measuring the whole unit. It's largely based on how good of a reflector you have behind the lights. like if behind the light socket's it's just the black hood, it won't reflect the light into your aquarium which gives you a lower rating but if you put tin foil back there, it's going to bump it up quite a bit!
So anyway, if you get some CFL's to replace your lights with you'll easily get medium lighting and might be able to sustain some high light plants since it's a low tank, the plants wouldn't be too far from the light. For right now your lighting is below low light rating.
Oh also get a CFL that has at least 5,000-6,500 Kelvin rating. 6,500K being better because they are brighter and it mimics the sun on a clear mid-afternoon day where the sun is at it's peak and it grows plants the best. The lower you go, the dimmer the lights are basically. usually Incandescent's are around 1,000-2,000K...no good!
Hope that helps some!