Searching and replacing HTML can be tricky. For example, what
about HTML like this:
However, if you simply want to replace their picture
with yours, use a regexp:
but you'll also want to remove and/or replace any
WIDTH, HEIGHT, and ALT tags as well.
....which get real complicated real quick. Consider
using a module to parse the html, or write your own little
subroutine to parse each instance of the IMG tag...