PERL or grep help pls (search replace)

[Chad A. Adlawan]

hello,

   i have like 10 thousand small files, some containing the text 
"http://209.155.163.97/smile.gif"; inside it while some dont.
   can someone please help me with a script w/c views all these files and if it 
sees a "http://209.155.163.97/smile.gif";, will replace it w/ a 
"http://www.cproda.com/smile.gif"; ?.

   thanks a lot :-)

chad