A puck light is your best bet. Xenon bulbs are cooler than halogen. But to be fair, they both put out heat. I've been very successful with LED puck lights. There is no heat and the projection is great. You have to be careful though. There is a lot of junk out there. But look for a three watt unit- usually it has 3 one watt LED diodes in it. It's not as 'warm' as an incandescent, but it's not cool like fluorescent. Sort of in the middle. And it will effectively last forever. Good luck.

Generally, a good quality low voltage under cabinet light will give you no problems. The transformers are small enough to fit behind the 1.25" valence very easily. Line voltage, generally by definition, is bigger than low voltage. The wires are thicker, the bulbs are bigger. Since there is virtually no threat of shock with low voltage, you can get away with thinner wires and smaller connectors. Although xenons burn cooler than halogen, you won't feel a difference if you touch them. They'll both feel HOT. But don't let that dissuade you. I've specified thousands of feet of xenon strip light for under cabinet with 100% success. NSL has a product which can possibly work for both of you. It takes a line voltage input, but has an integrated transformer. It comes in various lengths and colors. It's 1.25" deep, so it'll be slightly more visible than a thin low voltage strip light. But it can be a good compromise. I've used it very successfully as well. Here is a link that might be useful: NSL Under Cabinet Xenon Light

We also have xenons (Kichler, 12v direct wire w/ 18w xenon bulbs - about 7 units installed under our cabinets about a year ago) and, while the cabinets directly above do get warm, they do not get hot. That's to be expected given that these are incandescents and will produce heat that will be absorbed into the cabinets if left on for long periods. Ours are not dimmable but they do have a high/low switch and we keep it on low - unless the lights are being used to illuminate a task. Will they damage wood cabinets? That depends on the wattage, the transfer rate of heat to the wood (which could be influenced by the design of the fixture and/or how it's mounted and the degree of air circulation) and how long the lights are left on. It might be enough to discolour some finishes or even bubble up some veneers directly above the lights (depending on the adhesive used - but I would expect that this would be extreme) but I wouldn't worry about anything truly wretched here - provided the light fixture is not overly enclosed. Last year, I spoke with our cabinet supplier about the choices and they overwhelmingly recommended xenons. FWIW

I'm very happy with the decision I made! I'm taking the puck lights back to the store and am getting Seagull low-voltage linear lights as so many on this forum have recommended. They're still Xenon so have a warm color, but they're about 3/4" instead of over an inch as the pucks are, and they seem to hide really well under there. Also the individual light holders clip onto a thin track at any location you want so you can have as many or as few as you need along the track (adding more later if you want more later, for example). They'll work w/ a dimmer so I'll get a dimmer which means I'll need a transformer hidden somewhere (probably in the basement, below the kitchen). I visited a local store that had them on display so I got to see how they look and I was very impressed. :) Down side: they cost quite a bit more (for my situation: about $160 I think (?) not including the transformer and dimmer). But for me I didn't really feel I had a choice, considering my 1913 cabinets sit far too close to the counter (14") so there's really no way to add some trim below the cabinets to hide the less expensive but significantly thicker lights - and I didn't want them sitting too far back which I've read is poor task lighting and creates shadows. Here's a link that shows the system: http://www.SeaGullLighting.com/Linear-Lighting.htm And below is the actual lampholder (out of a few choices) that my local lighting store suggested I get. She said she liked that these because - rather than being a 10W light - these are two 5W lights in one holder, which end up having a softer, warmer effect while being just as bright for task lighting. She may have said they might be a hair thinner, too. Since I mostly want these for ambiance/mood lighting, I felt I should go this route (same price as the other options, or actually maybe a few cents less). But being such a research hound I'll probably inquire about them on this forum at the last minute before purchasing...just to play it safe. ;) http://www.SeaGullLighting.com/1372/Ambiance-Low-Voltage-Lighitng-9428-15.html Good luck yourself! Here is a link that might be useful: Seagull low-voltage linear lights