http://www.directron.com/psu.html
http://www.pcguide.com/ref/power/sup/index-c.html
These pie charts show vividly why you should pay attention to your power. Despite
their low cost compared to other PC components, power and cooling are responsible
for a large percentage of overall system problems. Despite this, many people who
would pay $200 to get a CPU 10% faster than another one--even though it will make
almost no noticeable difference in performance and will be obsolete in months--won't
pay half that for a quality power supply that will last for years and years.
(Source: Strategic Research Corporation, via PC Power & Cooling, Inc.)