I used to use sidemount flourescents but found they were too noisy, and flickered. Also I don't like that the lighting isn't 'continuous' where as with the "puck" style of lites, I can add or remove easily to my desired lighting pattern.
I use Liteline brand products (www.liteline.com
), for undercabinet lighting, I prefer the "puck" style round lamps with the Xenon 20W bulb. They last longer, run cooler and give off much brighter and whiter lite than the flourescents.
When doing a new install, I simply place the 12V xfmr and 110V switch lead in a junction box inside the cabinet or other accessible space, or in the basement below and run 18-2 wire to each puck lite. Simply size your xfmr to the total wattage of all your lamps.