I use Access DBs for some quite high volume websites and never once experienced a problem, tbh.
I suppose it depends on how much you are reading from and writing to it, how often you are doing it, how you are using it, so its difficult to say at what volume of visitors you will experience problems, if at all.
Tnx for your reply Glenn.
It's good to know that you don't get any problems.
The reasen I asked it, is because in my first ASP lesson (trhee years ago) my teacher told me that.
But I did not noticed something from it, ever since.