converting a web page

I've written a little program to carry out a process similar to that of the dialectizer at http://rinkworks.com/dialect/ it loads a web page and then runs through the page translating certain words and phrases I would appreciate any comments or advice on the the process I've used and whether anyone can think of improvements in speed and efficiency that I might implement. The conversion dictionary is stored in a mysql database in two columns preconv and postconv I load this into a array and then iterate through the array using the following while ($row= mysql_fetch_array($sql_result)){ $page = eregi_replace("$row[0]","<b><font color='#FF0000'>".$row[1]."</b></font>",$page); } I've chosen eregi because the case insensivity is important. Any thoughts or comments? Allan