One thing I have not seen mentioned on this thread is making sure you have
the correct inverter for what you want to use it for.  For sensitive
equipment, VCR's, etc. you need a pure sine wave inverter. I found a writeup
(the first Yahoo hit I got) at
http://www.donrowe.com/inverters/inverter_faq.html#modified .

Those cheap inverters are creating AC current that looks like this _|-|_|-|_
.

The pure sine waver inverters are more expensive per watt output but beats
replacing a piece of equipment that did not like square AC current.

I have several inverters. When in doubt I use the good one.

Bryan