Concur with max and kevin.
Access + 200 users = imperceptible movement. Snails would zip by you. Watching grass grow would be truly exciting. You probably could not stand the strain of watching something so fast as a sloth eating.
Use ORACLE, SQL Server, heck - even MySQL would be better than Access in this case. (But MySQL is kinda undersized for this, too, when you get down to it.)
Oh, by the way...
Access is NEVER the server side of client/server. You can build ADP stuff that will look at an Access database, but you won't be using Access itself when you do. You need a special license for IIS (if I recall correctly) in order to do this.
Access as a FRONT END can be the CLIENT side of a client/server situation with ORACLE or SQL Server as the back end. Works pretty well. Can be costly, though, 'cause you need a separate copy of Access for each user. Add it up. 200 users * Bill Gates's price structure = big budget nightmare.