Coyote, that LED link is a bit outdated. LEDs have come a long way. They used very small diodes, which won't do much for plants. You really need high-power diodes. I've got a high-light 20H planted tank using 30W of high-power LEDs. It's all about PAR (photosynthetically available radiation) and good LEDs and T5HO bulbs put out a lot of PAR.
As far as fluorescent vs. LED, kevkev pretty much nailed it. T5HO fluorescents can give you a lot of PAR, but you have to deal with bulb replacement. LEDs have a high buy-in cost, but they're more energy efficient. You can DIY an LED fixture for far less money than the cost of a lesser commercial fixture. I've got ~$100 into my fixture and I could have built it more cheaply if I knew what I was doing at first. It's probably even a little overkill for my 20H. The LED link in my signature has more details.
Eagle, be aware that if you want a med-high to high-light tank, you'll need to dose ferts and inject CO2. Without CO2 injection, I had GSA all over the glass in my tank within 24 hours of installing the LED fixture.
