We bought a pre-lit tree in 2008. It had like 750 incandescent bulbs. In late 2009, Home Depot had a heck of a deal on strings of LEDs. I stripped the old bulbs off and rigged up 750 LEDs on the tree. Energy consumption went from about 375 watts for the Incandescents to about 73 watts with the LEDs.
We're savin' the planet:)
Sue doesn't particularly like the LEDs for some reason.