When you thought the whole world is using multi-core micro-processor, remember that I still have a single-core computer at home. Likewise, we still see legacy web applications who use Access as database. But it is time to upgrade to a real powerful database for web applications, guys.
I cannot count how many times I put down the words in a forum in the past, but it is today that I found the words written in a Microsoft whitepaper. I know it is an old one, but the words are clear enough.
Access isn't designed to create Web sites. The Data Access Pages are of limited use in intranets, but not on the Internet. The underlying Jet engine is also not useful, except when the number of simultaneous users is low. Access is optimized for Windows, and not for the Web.
(from Page 14 of “What’s Right in Your Organization”, which can be found from this page)