I am making a website for learning languages online for free. I am
most likely going to use Drupal (http://drupal.org) with a MySQL
database (http://mysql.com) to manage the content (unless you suggest
a better system given my needs).

I have seen the beautiful way that Answers.com (http://answers.com)
seamlessly imports content from Wikipedia into their website.

I would like to do the same thing with specific Wikipedia pages
(relating to languages, language learning and linguistics).

To clarify, this would include:

1) the initial importation of information from selected Wikipedia pages

2) automatic checking and updating of content on a regular basis to
match the current data on Wikipedia

How can I achieve this without spending a fortune?

(1) Go to the wikipedia page you want, click 'printer ready version'
on the left, get the resulting url

(2) go to the drupal page you're trying to create. Change it from
"filtered HTML" to "Full HTML"

(3) Enter your body text as "<iframe src ="(the url in #1)"></iframe>"