10 watts is not enough for a planted tank, especially 100g. It also depends what kind of plants you are getting, there are different plants that prefer different lighting types, such as low light, moderate light, or high light. If you're getting low light plants you only need about 1-2 watts per gallon, moderate 2-3, and high anything above 3. You can get some nice moderate-high lighting with a couple of T8s or T5s. I'm having the same problem as you currently except mine is getting what kind of bulb. I suggest getting a moderate lighting fixture for now, it will allow you to grow some nice low-moderate light plants; and if you decide to get some high light plants down the road you can just upgrade your light fixture.
Oh also if you don't want go the fluorescent tube style you can get a couple of high wattage CFL bulbs.