God.. now I remember why I started going to Yahoo Groups more for my fishkeeping forums. I just typed a LONG reply and when I clicked the Post button, the dang website bogged down and I lost my reply. I wish ALL forums allowed email posting of replies. I'm re-typing most of my reply below and copying it before I click the Post button this time. LOL
Wattage is NOT the thing to compare when comparing lighting. Wattage is the amount of electricity a bulb uses. For example, a 60W incandescent bulb uses the same electricity as a 60W fluorescent tube and obviously the 60W fluorescent puts out a LOT more light. A 60W CFL puts out more light than a fluorescent tube. 60W of LED puts out more light than any of the above... but LED lighting is still pretty expensive. Most of the aquarium kits will have standard fluorescent tubes with some of the 10G kits actually having room for two incandescent tubes (which can be easily upgraded to CFL lighting screw in tubes to get a LOT more bang for the buck).
Kelvin is the color spectrum of the lighting with a soft white incandescent bulb being down in the 2500K range and then the bulbs would get much *brighter* as the K rating goes up until the K rating gets too high and gets into the blue/ultraviolet ranges that are used on many SW Reef tanks to make the corals and fish pop in color... but if you are going to have live plants, then you would want to stay in the 5,000K to 8,000K range, with 6500K being the best as far as a general purpose aquarium bulb.
Lumens is how *bright* a bulb is as far as visible light to the human eye although the K rating also plays a big factor in our perception of the bulb.
That said, for the kind of white you are probably looking for a Daylight or Sunlight type bulb but don't just rely on those names. LOOK at the details on the bulbs.
I've seen same sized, watt and Kelvin bulbs where one would only have 1250 lumens and the other would have 3250 lumens, meaning it would be 2-3 times brighter... sometimes for only a little more money and even less on occasion, depending on the brand, sale prices, etc.