If you use Access you will have implement security on the database which will cause all users (even non web-based ones) to have to login to the database. Access is also not really the best choice for a web backend. If cost is an issue, consider MySQL or some other free database that is better desinged to be accessed from the web. You will need to use something else (ASP, C#, etc) to create the user interface. And do not do this until you read up on database security and SQL Injection attacks.
"NOTHING is more important in a database than integrity." ESquared