MySQL vs Flat File

I'm looking at several PHP (and Perl) scripts to do a certain job. Some use Flat files for the data and some use MySQL. I guess I already know MySQL is probably faster. My conern is, if we choose a flat file program. How much data can it handle before it becomes sluggish? On a related note, does anyone here know of a GOOD program in PHP to do classified ads? One major thing we need is the ability to charge for posting an ad. The hotscripts.com and other PHP code sites have come up dry with anything remotely good. -- Thomas Deliduka IT Manager ------------------------- New Eve Media The Solution To Your Internet Angst http://www.neweve.com/