I have seen recommendations advising people to have at least 100Watts of power and other foolish statements.

Generally speaking, more power is better but should not be the determining factor when making a decision. You do want to match your amp to your speakers somewhat, The loading impedance (efficiency) of your speaker will have a lot to do with your power requirement. If you have a little book-shelf speaker you can obtain pleasing sound from an appropriately rated amp of 30 to 50 Watts. The efficiency is usually noted as db/W, meaning how loud (db - decibel) a speaker will play if given 1 Watt of power at a distance of 1 meter. Most speakers will be rated at ~ 80 - 95db/W, but there are plenty with a much lower rating - requiring a larger amp to achieve the same loudness, as well as many 'high-efficiency' speakers producing over 113db/W - meaning that they do not require that much power. Lacking this rating, one should be able to assume that larger speakers will require more power due to the amp having to move larger, heavier magnets on bigger cones.

The other item is the inconsitent, misleading way amplifiers are rated today. Many moons ago when an amp was rated/ advertised at 100 Watts, it meant that the amplifier could continuosly deliver 100 Watts per channel while maintaining it's rated distortion levels. If you look at todays advertisements you will find that the same statement is describing an amplifier having the total, maximum capability of 100Watts. Divide the number by the amount of channels and in the case of a stereo amp you are now down to 50 W/ channel. However, this being the maximum capability of the unit, you will not be able to maintain this power level over longer periods of time or without distortion; this means that you are actually buying something realistically delivering 30 to 35 Watts per channel.