This thread would not have been renewed except that a spammer somehow found it and posted to it. Otherwise it would be sitting in oblivion.
If you haven't noticed yet - this thread about expeired passports being valid is from
FIVE YEARS AGO.
We now recommend passports to Mexico and Canada. You may be able to get by without them but it is a very excruciating process. Here is where you go for updated info:
http://www.getyouhome.gov/html/lang_eng/index.html