Problem with vowels usinc accent mark

Hi everybody, i have a small problem and i hope anybody can point me in the right direction... I have some info that i retrieve from a mysql db. The info in these fields is entered by my customer, and most of the times he is using uppercase. When i show the info on my browser i apply ucfirst(strtolower($string)) and everything shows ok. I develop on a Windows XP + Apache 2 + PHP 4.3.4 as a module. But when I upload the site to a production server, strings are ok except that vowels with accent mark are written in uppercase. e.g. "Producto para instalaciÓn sin cables". Production server uses linux + apache (don't know which version) + PHP 4.1.2. I tried to include a setlocale(LC_ALL,"es_ES") on my code, but nothing happened... Any help will come really handy!