I saw where someone answered this already for a PHP solution. Are you selecting these two timestamps out of a mysql database? if so, there's a simple way to do it in your actual query.
SELECT now,then,TO_DAYS(then) - TO_DAYS(now) AS diff FROM your_table
or, if now is always '2000-11-07', then use:
SELECT then,TO_DAYS(then) - TO_DAYS('2000-11-07') AS diff FROM your_table
Then you'll have $diff after you fetch the information.
You can also set up something like this in your where clauses to only select rows that are older than X days, or delete them, or whatever. Let me know if you have any questions, if this is even what you're doing.. 🙂
---John Holmes...