Uplights for trees need to be mercury vapor. They offer the silver (moon glow) effect that most people like. The bullets can be mounted remotely from the ballasts (say, up in a tree). They'll last 5-7 years without being touched. You can use regular outdoor floods but they are much better as security lighting on a motion light hanging on the side of a garage.
My 70 year old mom and every handyman in the country puts in the Malibu low volatge light. You need to separate yourself from the crowd of wannabes. The low voltage stuff lasts 1-2 years before somebody wacks one with a weed wacker or the kids step on it in the snow.
Best place to order the HID's is from TechlightUSA. They are bullet-proof but carry a heafty price tag (between $120 and $200 each). We use different wattages depending on the application, generally from 50W to 100W. There are higher wattages but you might be better off putting in two smaller ones instead. You can get them with 2", 3" and 4" diameter shells.
I don't generally like to spec out a manufacturer but we've had good luck with that one.
Good luck Tiger.
[This message has been edited by PE&Master (edited 07-29-2006).]
