Clyde- The best way to get into the LED game is by using the LED retrofit lamps (like the illumicare) since they are essentially based on the benchmark of the halogen lamps we are used to. Look at the manufacturer's specs to tell what sort of light you'll get. A 20w halogen (BAB) equivalent may be a 4w, 5w, 6w or 7w LED depending on the manufacturer. Get a couple and demo them, play around with them and see what works before ordering the lot and finding out they're not what you want. The other option is to go with a proprietary LED fixture manufacturer (eg. Kichler, FX, Cast, etc). You'll get a better warranty, but your design flexibility may be more limited.
If you want more specifics, post a picture and a sketch of the project and the people here on the forum would be happy to overwhelm you with design ideas, installation techniques, product opinions, personal hygiene critiques, etc!