You also save some electricity. It appears that a LED light can be about half the wattage as a PC light for the same light intensity. That also gives you "green points" with the green crowd. And, I'm sure there will eventually be easy to use devices available to power the LEDs without spending so much.
Also, I visited my surplus metals store and found that aluminum plate is $3 per pound, pretty cheap, and they had some aluminum channel, at $15 per 8 feet like:
This channel is perfect for a row of LEDs. It is thick enough to be a very good heat exchanger, and just the right size to mount LED "stars" on it, with fan cooling behind.
For an 18 inch long piece that would only be about $3 for each row of LEDs. If there were enough interest I would be willing to buy an 8 foot piece and sell it at cost, plus shipping. Heat sink extrusions start at about $20 per foot.
I apologize for hijacking the thread, but at least this is on topic to some extent.