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if you had a whole bunch of *.html files you would create a file say called editfile, this file would contain:
then edit all the files using the following command
sed -f editfile *.html
the edit file can contain multiple lines, each doing a different substitution.
This might be what you're looking for?
wget -r -k [yourwebsite.com...]
-r is for recursive
-k is to convert non-relative URLs to relative
To find the free program, a google search on wget win32 will work