when you buy new PCs from dell, they have free old computer disposal option.
Otherwise, you can sell it to a salvage company, they'll take it for free.
Don't pay those companies that do recycling, who are they kidding...
Finally, if nothing else works, see if you can donate it to goodwill, or a local school.
don't throw it in the garbage because it has lead in it...
same thing as those used up UPS batteries, don't throw those away either...lead acid = bad for environment! Get those charged up at batteries plus or have them dispose for you.
You'll sleep better at night.
-FP