> Once I took it to a garage that had one of those pressure/vaccum
> coolant
> exchange systems. The old antifreeze was simply collected in their
> holding system for disposal along with their other liquids like oil,
> brake fluid, etc, etc, etc.

this is the quickest and usually the easiest method of getting the old
used coolant out of your garage. i use the Jiffy-Lube or Presto-Chango
or whatever is nearby ... ask first, though. most of them sell the old
coolant and oil so they don't mind at all if you come down and dump
more coolant and oil into their storage tank-thingies. only thing is,
don't expect THEM to do the dumping. you get to sit there, pouring it
out of soda bottles or whatever you stored it in. :)

but it's better than dumping it on the lawn and diluting it with
water, and waiting for the sunshine to break it down chemically. also
better than dumping it into the toilet and flushing it away ...
although having worked in a sewer plant for a while, this really
doesn't hurt anything unless an awful LOT of people do it in the same
city on the same day. by the time household chemicals (like bleach and
liquid plumber and such stuff as that) get to the plant, it's so
diluted with all the water and waste that it isn't really a problem at
all.

hope it helps!
unca joel