Since you a building in a while, the technology will be even better, but I just installed 15 CREE LR6 LED lights in my house. They are amazing. The light quality is better than the 75w incandsecent floods they replaced and they use only 12w each. They last for 20 years or longer, so there's no need to replace them for a long time. That helps because I have a few of them in a 20 ft ceiling. They emit less heat than incandescent and the heat they do emit goes into your attic, not radiating into your living space; therefore, your A/C does not need to work as hard. They are also dimmable down to 25%. They take about 5 minutes to install into a standard 6" can. I just really can't say enough about these lights. ALSO, CREE just released a new chip that gives off even more light at only 5w I think. They are expensive at about $95 per light (6 months ago, maybe slightly cheaper now), but they will pay for themselves in about 3-5 years depending on usage. NOTE: That's only in the electricity they save. That doesn't include using less energy to cool my house, or all my time and money/gas going to the store to buy replacement bulbs and replacing them.
I also own stock in CREE and highly recommend it, especially if you can pick it up in the low 20's.
Many people haven't got a clue at what real LED technology is about. They see those cheap flashlights and crappy products at walmart. This is a serious technology and next time you are on a plane or driving down the highway, take a look around; every light you see will be replaced with an LED light over the next 20 years. Congress already passed a bill banning incandescent lights by 2014 I think. CFL lights are a good alternative for now, but they suck compared to LED. They use at least twice as much power and their lifespan sucks. Most CFL's last only about half as long as their stated lifespan and we all know that their light quality is sub par and they take time to warm up. CFL's are also terrible for the environment because they contain mercury and lead. LED's are completely safe for the environment to dispose of.
