Those bulbs will give you more than enough lighting to grow just about anything.
IMO, with what you have (fixture) the screw-ins are a very nice option and the way to go.
I suggest, before buying them that you check the kelvin ratings on the bulbs. Many of them that are available are the lower kelvin ratings (2400K 4000K) and will give a yellow-green cast to the water.
You want something in the 6000 - 9000K range for a more natural daylight look. The plants will grow well under the lower K ratings, but you probably will not be happy with the overall look of the tank.
If you can't find the upper ratings locally there are sites which sell the bulbs with daylight ratings available.
Len