I have used MySQL with PHP and for most DB driven web sites it works fine. I would say the big plus point is that it is free and simple to learn. The big drawback is that some of the more advanced functionality in access is not present in MySQL.
I must admit I have not tried to use PHP with Access, we use ASP or my clever Dick mate uses Java on the on the server side script.
I don't think there will be too much problem you just have to use Access SQL string statements from PHP as opposed to MySQL, they are very similar. Setting up the connection and security protocols may be a bit more involved though.
One thing I have heard, though cannot guarantee, is that there are license issues pertaining to client side querying of MS access.
I would steer clear of Jet and Use the Access project engine if you want to start using access as a server side DBase for Web applications.
