There is an alternative which is to setup ODBC tables in the MSAccess front end which accesses the tables on the MySQL server. This way the database remains central and then the second phase would be to create the PHP front end. The pressure will be less as there is already a working solution.
I will have a look around the internet to see what the various options are, including conversion tools etc.
I think the main thing is to have something which is free, so I am not tied in to .NET, ASP.NET etc. It may be better to break away from ms completely on this one and look at moving everything into MySQL and having a new front end (PHP?), even if this is a more time consuming process.