Thats a 40 gallon tank correct?
2x30 watt lights should be enough for many common plants... but will not be enough for more demanding plants. You may find that some plants will be a bit "leggy" in terms of growth, or just won't grow at all... or in extreme cases, just die. On othe other hand, other plants will simply thrive.
If you want a simple plant tank... I suggest getting some floating plants (duck weed is a simple one to grow) and allow that to cover about 50% of your tank's surface, and some lower light plants (some simple ones that come to mind are java ferns/mosses, anubias, etc.). What I would personally do is have a medium-large sized piece of driftwood in the center of your tank... with anubias and java ferns attached to it with some floating plants near the top of your tank. Add in a around 10 neons, and in a couple of dwarf gouramis, and it'll be a pretty nice tank.
BTW, CO2 injection will benefit just about any plant tank... low tech, or high tech.
HTH
-Richer